Barrel - Part 1

Explanation:
The comic shows a young boy floating in a barrel in an ocean that doesn't have a visible end. It comments on the unlikely optimism and perhaps naïveté people sometimes display. The boy is completely lost and seems hopelessly alone, without any plan or control of the situation. Yet, rather than afraid or worried, he is instead quietly curious: "I wonder where I'll float next?"  Although not necessarily the situation in this comic, this is a behavior people often exhibit when there is nothing they can do about a problematic situation for a long time; they may have given up hope or developed a cavalier attitude as a coping mechanism.
The title text expands on the philosophical content, with the boy representing the average human being: wandering through life with no real plan, quietly optimistic, always opportunistic and clueless as to what the future may hold.
The isolation of the boy may also represent the way in which we often feel lost through life, never knowing quite where we are, believing that there is no one to whom to turn. This comic could also reflect on Randall's feelings towards creating xkcd in the first place; unsure of what direction the web comic would turn towards, but hopeful that it would eventually become the popular web comic that we know today.
This is the first in a six-part series of comics whose parts were randomly published during the first several dozen strips. The series features a character that is not consistent with what would quickly become the xkcd stick figure style. The character is in a barrel.
In 1110: Click and Drag there is a reference to this comic at 1 North, 48 East .
After Randall released the full The Boy and his Barrel story on xkcd, it has been clear that the original Ferret story should also be included as part of the barrel series.
The full series can be found here . They are listed below in the order Randall chose for the short story above:
[A boy sits in a barrel which is floating in an ocean.] Boy: i wonder where i'll float next?
[A smaller frame with a zoom out of the boy in the barrel seen from afar. The barrel drifts into the distance. Nothing else can be seen.]


Petit Trees (sketch)

Explanation:
This comic does not present a particular point; it is just a picture drawn by Randall .
The Little Prince (in French Le Petit Prince) is a novella written by Antoine de Saint-Exupéry in 1943, about the titular Little Prince, who lives on an asteroid and visits other inhabited asteroids and eventually the Earth. The book is filled with drawings of the asteroid, the prince, and the travels they make. It is noted how, on occasion, baobab trees can begin to grow on these asteroids, and should they not be immediately uprooted, the growth of their roots would tear the asteroid apart. In this drawing, the roots are encircling the sphere, rather than piercing it, as Le Petit Prince describes.
The Little Prince has later been referenced both in 618: Asteroid and in 1350: Lorenz at the end of the space trip branch. It was also referenced to in the What If article Leap Seconds .
[Two trees are growing on opposite sides of a sphere.]


Island (sketch)

[A color sketch of an island.]

Explanation:
This comic does not present a particular point; it is just a picture drawn by Randall .
The title text may be a play on the classical "Hello, world!" program, traditionally a first program when learning a new programming language.
[A color sketch of an island.]


Landscape (sketch)

Explanation:
This comic does not present a particular point; it is just a picture drawn by Randall.
There is a joke in the title text that a river, made of water, is flowing through the ocean, which is also made of water.
It is also worth noting that the sketch, when flipped vertically, maintains the appearance of having the sea on the bottom and sky on top, although the setting sun is on the wrong part of the horizon.
Similar to works of M. C. Escher , this picture takes visual components of a typical scene and combines then in ways that appear to work well on a small scale, but would never combine that way in real life and do not make sense in the larger context of the image.  The clouds are casting shadows on the sky.
[A sketch of a landscape with sun on the horizon.] [There is text from the checkered paper at the top:] From Page No.__


Blown apart

Explanation:
This comic is a mathematical and technical joke involving prime numbers and primary colors.
In the comic, an anthropomorphic black-colored number 70 sees a package, but it turns out to be a letter bomb that explodes when opened.  The result is pieces of the number scattered about.  The specific pieces are a red-colored 7 , a green-colored 5 , and a blue-colored 2 .
The title text explains the logic for splitting 70 into 7, 5, and 2; as with many of the earlier comics, the title text explains the joke rather than adding to it. 7*5*2 is a prime factorization of the number 70. Prime numbers are numbers that cannot be divided by any number other than itself and 1. Factors of a number are numbers that can be multiplied together to produce that number (i.e. 2×5×7 = 70). 70 has other factors, including 1, 10, 14, 35, and 70, but 2, 5, and 7 are the only factors that are prime. All other factors of 70 can be formed by choosing zero, two, or three of the prime factors and multiplying them together.
An implication of this comic is that prime numbers would be immune to explosions, as they are already their smallest parts.
Although not explicitly called out, the colors of the numbers also seem to have been blown apart.  Red, green, and blue are the primary colors in the additive color model.  These colors mixed in pairs produce cyan, magenta, and yellow, which are primary colors in the subtractive color model.  The removal of all additive primary colors, or conversely, the combination of all subtractive primary colors, produces black, which is the color of the original 70 (according to the official transcript , although it looks dark blue in the drawing).  The comic is somewhat misleading in that red, green, and blue do not compose black in either color model, but the difference between the two models is not widely understood (most still view the additive primaries as red, yellow, and blue).
[A black number 70 sees a red package. This small panel is partly overlaid on the next larger panel, which is shifted down.] 70 70: hey, a package!
[The package explodes in a cloud of brown smoke. This panel is both behind the first in the top left corner, and below the last panel, which has been laid on top of that corner.] BOOM
[There are a red 7, a green 5, and a blue 2 lying near a scorched mark on the floor.] 7 5 2


Irony

Explanation:
It must be part of the human condition that causes us to think that odd statements are sometimes more humorous than those supposed to be funny. Cueball makes a true statement, that his statement is not very funny. However, because he invoked irony and thus makes it self-referential, the sentence is now funny! The other guy (also a Cueball-like character), producing a fake laugh, is probably not so sure that it is actually funny.
Now going meta: In 20,000 years, there might be no more humans on earth to find the irony funny anymore. How ironic ! Alternatively, the barren landscape would have occurred regardless of whether someone made the joke, so ironically, the cautionary tale is completely meaningless, although still funny.
This is the first xkcd comic showing stick figure people, which eventually becomes a defining characteristic of the future comic series. It is thus also the first comic with Cueball (and the first with Multiple Cueballs ). Note however, that it was actually not the first comic Randall released using either of the above mentioned features, see the trivia below.
The "too much perspective" line comes from the visit of Spın̈al Tap to the grave of Elvis Presley . In addition, the perspective theme also invokes the Total Perspective Vortex in The Hitchhiker's Guide to the Galaxy . This is located on the desolate planet Frogstar B, possibly looking not unlike the final image in the comic.
Self-references was already used again in 33: Self-reference , and again and again , but never more famously than in 688: Self-Description .
[A panel only with text. The last text is written below a line in all capital letters.] When self-reference, irony, and meta-humor go too far A CAUTIONARY TALE
[Cueball talks to to his Cueball-like friend.] Cueball: This statement wouldn't be funny if not for irony!
[Cueball laughs at his own joke in front of his friend.] Cueball: ha ha Friend: ha ha, I guess.
[Again a panel only with text.] 20,000 years later...
[A desolate brown badlands landscape with an imposing red sun in the dark blue sky.]


Girl sleeping (Sketch -- 11th grade Spanish class)

Explanation:
This comic does not present a particular point; it is just a picture drawn by Randall. It is just what the title says - a sketch of a girl sleeping drawn during a Spanish class.
According to the title text, she is also on the floor.
[Girl sleeping on her side, facing away from view.]


Red spiders

Explanation:
The early comics often feature a style different to what would become the signature xkcd stick-figure style. This comic is the first in an arc of comics, spaced out over 3 years (so far), in which Red Spiders are seen attacking humans. Its objective is not to be funny, philosophical, or scientifically interesting; it just tells a story, in a Questionable Content -esque way.
Interestingly, the red spiders actually more closely resemble opiliones, the order of arachnids that includes the Daddy Longlegs, and which are actually more closely related to mites than to spiders. Of course, the number of legs is incorrect.
The full series of Red Spiders comics:
[Many six-legged red spiders standing on and hanging from cuboids. The cuboids hang in the air with no visible means of support. Some of the spiders have made a bridge out of themselves.]


Serenity is coming out tomorrow

Explanation:
This comic is about the release of the movie Serenity , which was the followup to Joss Whedon 's TV show, Firefly , which was cancelled by Fox after only one season. Plus, three episodes were not shown on Fox but debuted on Sci Fi Channel in the UK. The show was followed by a devoted number of fans who were outraged by the cancellation of the show. High DVD sales and strong fan support allowed the follow up film Serenity to be created, which tied up many of the loose ends that Firefly left open, such as the cause of River 's abilities and the origins of the Reavers .
The image shows the main characters of Firefly. From left to right:
This is the first xkcd with adorned stick figures (e.g. hair, coats, etc.) to represent distinct characters, which later becomes a standard motif of the comic.
Nathan Fillion , Summer Glau , and Jewel Staite , the actors who play Mal, River, and Kaylee respectively, show up later in Randall's series The Race .
[Several stick figures stand side by side in a lineup. A forlorn male in a coat, a male with combed hair, a male with spiky hair and arms outstretched enthusiastically, a female with long hair and cornrows, a shorter female with stringy hair falling over her face, an enthusiastic female with arms raised in celebration with shorter hair, a male with short hair and a goatee and hands on hips, a female with curly hair wearing a dress, and a stern-looking man with flyaway hair.]


Pi Equals

Explanation:
There are two possible references here. One is from the book Contact by Carl Sagan, where the existence of God was shown in the last chapter to be encoded in the digits of pi . The other is an old joke of a fortune cookie with a fortune that reads, "Help! I'm trapped in a fortune cookie factory!" Similar jokes are often repeated for any mass-manufactured personalized item, often implying that the worker who made the item is working in a sweatshop somewhere or is literally trapped inside a factory and calling for help via the items they produce. This joke is also referenced in 327: Exploits of a Mom 's title text, where Mrs. Roberts daughter 's name is "Help I'm trapped in a driver's license factory."
The most literal interpretation of the joke would be that some being who helped to create the universe in a "universe factory" snuck a message into the digits of pi (a number that has an endlessly long decimal that never repeats) asking for help to get out. Mathematical concepts being manufactured in a factory is the main mental image here. One can't help but wonder if the primordial beings who labored on the universe to produce things like the gravitational constant and pi have a labor union. Judging by the fact that they're calling for help, it seems they don't.
Since pi never ends and does not follow any sort of known pattern, if each number pair were assigned a letter from the alphabet, or if it was converted to base-26 (or preferably ASCII or some other form of text encoding, if you desire capitalization and punctuation), the entire works of Shakespeare, as well as any other expressible piece of information, including the message in this comic, could presumably be found (it is not really known that pi really has this property , but the absence of this property would in itself be an extraordinary coincidence); although the probability of finding any given string of numbers within a calculable range of digits of pi diminishes rapidly as the string length increases .
In the novel Contact by Carl Sagan , he includes a "Signature of God" (There was a link here, but the page no longer exists). In brief, the signature consists of a very long string of 1s and 0s far out (after some 10^20 seemingly random numbers) in the base-11 expansion of pi that when arranged in a square of a specific size yields a clear drawing of a circle with a diameter of several hundred digits.  The existence of this pattern was hinted to the protagonist by a member of an advanced alien civilization as being encoded in physics by an even more advanced civilization with the ability to create universes.
Interestingly enough, this could also work for pictures: if you assign a set of nine numbers to equal an RGB hexadecimal color value, eventually you will find the Mona Lisa.
In the title text, Randall notes that this became one of his most famous comics (at the time it was re-released on the new xkcd site on the 1st of January 2006.) He also notes that it was one of his first drawings for the site (it was the 11th posted originally). See trivia below.
[A huge π to the left, then a large equal-to sign, and then five rows of text.] π = 3.14159265 3589793help imtrappedin auniversefac tory7108914...


Barrel - Part 2

Explanation:
Like in the previous comic in the Barrel series, the boy is floating in the ocean in a barrel. The previous comic made a point about the uncertainty of life; here, the boy's lament at not finding a mother is pure sentimentality, as accentuated by the title text.
According to Freud, the first stage of psycho-sexual development is the Oral Stage, which relates to a baby's relationship with its mother.  The realization that 'mommy' cannot be found is the first point at which a person learns to stop trusting the world and realizes that the world is not always comforting and safe.
This is the second in a six-part series of comics whose parts were randomly published during the first several dozen strips. The series features a character that is not consistent with what would quickly become the xkcd stick figure style. The character is in a barrel.
After Randall released the full The Boy and his Barrel story on xkcd, it has been clear that the original Ferret story should also be included as part of the barrel series.
The full series can be found here . But below they are listed in the order Randall has put them in his collection linked to above:
[A boy sits in a barrel which is floating in an ocean.] Boy: none of the places i floated had mommies.


Poisson

Explanation:
Cueball expresses himself as a Poisson distribution .
A Poisson distribution is a distribution that shows the probability of a given number of events occurring in a fixed interval of time or space. The X axis typically represents the "number of events" while the Y axis is a decimal representing the probability (i.e. 0.5 for 50% probability) a given number of events will occur in that fixed interval of time or space. It is commonly represented by a bar graph or a scatter graph (sometimes with a line connection to show a trend, even though there is no actual value for non-integers).
What's important to note for this comic is that this distribution only has data points on non-negative integers and is not continuous through decimal numbers or (as the image text tells us) negative numbers because events can't occur 0.3 of a time, or −2 times.
After implying that the concept of a person being a mathematical distribution is irrational, Black Hat suggests he is "less than zero". Since the Poisson distribution doesn't exist or has no value at negative values, Cueball either leaves or disappears magically.
Hence, the punchline is the same as the title text: Cueball doesn't exist to Black Hat anymore, because he has a value less than zero. Another one of the early comics where Randall explains the joke in the title text.
Also, because a Poisson point process is memoryless, the figure claiming to be the distribution may simply be repeating the fact as a reference to this.
[Cueball is talking to Black Hat. Cueball has his mouth wide open and has both of his arms up.] Cueball: I'm a poisson distribution!
[Same scene, except Cueball has only one arm up.] Cueball: Still a Poisson distribution! Black Hat: what the hell, man. Why do you keep saying that?
[Cueball's face is gone, and he is not holding any arms up.] Cueball: Because I'm totally a poisson distribution. Black Hat: I'm less than zero.
[Cueball is gone. Black Hat is now whistling.]


Canyon

Explanation:
This is one of the early comics that explores a theme xkcd returns to often: the wonder around us, if we would just look.
Cueball and his friend (who also looks like Cueball) are having a discussion. After the friend asks Cueball what the time is, Cueball simply states that it is "now." Then there is a beat panel showing the two standing at the lip of a great canyon drawn in detail and color.
The friend claims that "now" is a boring answer, since it's a tautology , a functionally useless answer, and a bad joke all at the same time. Cueball, however, asserts that "now" is the least boring answer he could give.
It is typical for human beings to focus on mundane concerns, like a meeting they might be late for or a bus they have to catch, and take their familiar environment for granted, no matter how fabulous it might have been at first sight.
The title text explains that they stand on the lip of the canyon, which may not be clear if you do not look very carefully at the color drawing. There are two tiny stick figures at the edge of the canyon, near the center of the panel.  On the other six panels, there is just a ragged line, which thus obviously is this lip of the canyon.
[Two guys, both Cueball-like, are standing at a cliff's edge.] Friend: What time is it?
[Cueball looks at his watch in silence.]
[Cueball looks up.] Cueball: Now.
[The full scene is shown: the two men (barely visible) are standing at the lip of a huge canyon in a rocky, barren landscape. A pock-marked moon and a ringed planet are visible in the burgundy-colored sky.]
[The two guys are again seen standing at what is now known to be the lip of the canyon.] Friend: That's a pretty boring answer.
[Same scene as before.] Cueball: Is not.
[Same scene.] Cueball: It's the least boring answer imaginable.


Copyright

Explanation:
Following the copyright wars can be tiring and irritating, but faced with the beauty of nature, the importance of such matters withers away.
Copyright is a monopoly granted by governments to writers, artists, performers, or corporations to control the distribution, copying, and performance of their creative expression or the creative expression of artists under contract with them. Before the digital age, it allowed authors and publishers an opportunity to profit from their work without fear of someone making copies and selling them for their gain.
In the digital age, when the cost and difficulty of copying has been reduced to near zero, it hasn't worked so well, especially for publishers of music and video. Industry trade organizations like the RIAA and MPAA have fought to preserve their old business models, lobbying for new laws to protect their income streams in an age where anyone can copy an MP3 file or a DVD quickly and cheaply. This has involved ordering web sites to take down "infringing" material (and many times material that wasn't infringing), media campaigns comparing file copiers to folks who commit murder on the high seas, and suing artists and writers who have used samples of music or movies in their own work. The RIAA has claimed that rampant illegal copying hurts the artists whose work is copied, as it cuts into the artists' royalty payments; many artists, on the other hand, complain that the RIAA's accounting practices have denied them their fair royalties for decades anyway, and that increased copying leads to increased fans and money through direct sales and is actually better for them than the RIAA.  It's a vicious war.
An early casualty in the copyright wars was Napster ; a later casualty was the concept of DRM (Digital Restrictions Malware) on recorded music and/or elsewhere. The wars have been going on since the early 1990s and show no sign of slowing down.
Slashdot and Boing Boing are two news aggregation websites that cover (among other things) the copyright wars in detail, usually biased against the RIAA, MPAA, and similar organizations.
[A colored drawing of a hilly, grassy landscape. Cueball is leaning against a tree.] Cueball: Sometimes I just can't get outraged over copyright law


Just Alerting You

Explanation:
Here, a man is seen riding on a Brontosaurus ? (This is according to the official transcript on xkcd, including the questionmark.)  Later Randall would probably have called it an Apatosaurus , see the Category:Apatosaurus .
The joke here is that this person feels the need to point out that they are "kind of strange," even though one might think that that would be clear from the fact that they are riding an extinct and potentially dangerous creature.
In the title text the man continues by saying Just thought you should know . Just a service notice.
In 650: Nowhere Megan is seen imagining herself riding an Apatosaurus.
[A man is standing on top of a green dinosaur and holding reins to the dinosaur's head.] Man: Before you talk to me, I should warn you: I am kind of strange
"I bet she's cool. I mean, she has a dinosaur! I'm gonna update this MWF for a while and see how that works. "


Monty Python -- Enough

Explanation:
This comic refers to the classic British sketch comedy group Monty Python , active primarily during the 1970s and early 1980s but also partly reunified in 2014 , whose humor style was frequently based on surreal jokes that subverted sense and logic. Their sketches are so popular that, as noted in the comic, many fans can repeat the dialog word-for-word, and often do. This comic points out the inherent irony of repeating a surrealist sketch, as surrealist humor primarily depends on presenting something the audience does not expect. By repeating the sketch verbatim among those who have already seen it, the listeners know and expect the punchlines and jokes. This is akin to a common ironic concept of a teenager who wants to rebel against conformity by doing all the things their friends are also doing.
The sketch in question here is the " Knights who say Ni " sketch from the film Monty Python and the Holy Grail , about a group of knights who protect certain sacred words, including the word "Ni" (pronounced like the word "knee," but shortened and with more staccato).
The comic suggests that readers continue in the surreal traditions of Monty Python, and provides an example: The character in panels 3-6 interrupts his retelling of the sketch with what appears to be a traumatic recalling of the time he saw someone run a woman over with their car and kill her, before returning to the sketch. The surreal humor is that the character dismisses the significant and serious comment he has just made by returning to the sketch as if nothing happened.
The title text refers to how fans of Monty Python can go for long periods of time simply quoting the sketches, as one person quotes a sketch, another recognizes it and says another quote without context, assuming everyone will recognize it. Perhaps a more contemporary version of this might be The Simpsons or Family Guy quote frenzies.
[The comic is drawn on blue-ruled graph paper.] [A Cueball with raised hands talks to two other Cueball-like characters and one Megan.] Cueball: We are the Knights who say... Ni!! Cueballs and Megan: hahaha
[There is only text in the second panel] Does anyone else find it funny that decades later, people are still quoting --word-for-word-- a group loved for their mastery of shock, the unexpected, and defiance of convention?
[Two Cueballs are looking at a hairy guy.] Hairy guy: We are the Knights who... oh, God, I'm so sorry
[Close up of hairy guy.] Hairy guy: So sorry, the car just came too fast and
[Words crumpled inside the panel, there's barely enough space for the hairy guy to the right and below the text. The last two words need to be to the right of him.] Hairy guy: She was right there and I saw her and then it was a blur and so much I ran to help didn't know what she wasn't moving I'm so sorry Hairy guy: so sorry
[The two Cueballs are looking again at the hairy guy.] Hairy guy: Anyway, yeah, Knights who say "Ni."
[The last panel is also almost only text. The text is centered. Below is a drawing that looks a flat infinity sign with two small lines at the center.] H on or Monty Python: promote surreal humor.


What If

Explanation:
This comic features a man and a woman in a romantic setting, surrounded by a fractal combination of love and doubts; an arrangement based on the Apollonian gasket construction. Three circles are drawn tangent to each other, then additional circles are added that are tangent to three existing circles (without overlapping), ad infinitum.
Randall's character design wasn't yet fully settled. Considering that Megan arguably was introduced two comics ago, and that the man has some hair, the couple might or might not be interpreted as Cueball and Megan.
Randall's later blog and book have the same name, what if? , though with very different meaning.
[A large black circle (drawn on grid paper) with white bubbles inside it, filled with hearts, question marks, and stick figure couples. The hearts are colored red.] [Bottom left circle - stick figure couple with a heart] [Top right circle - with couple:] what if this isn't everything it should be? [Two circles left of top-right:] i'm not even sure how i feel [One circle right of top-right:] what if i'm making a mistake?
"One of my best friends just got engaged. I really, truly think they're going to be very happy together." The friends referred to are Scott and Sarah.


Snapple

Explanation:
Cueball hands another Cueball-like guy an apple calling it a snapple. When the guy bites into it, his teeth go clink against the apple's metal surface; Cueball has infused the apple with tin.
The fourth panel is a silent wide shot, perhaps suggesting the joke was met with silence as a weak joke . As a meta-joke, the final panel might jokingly suggest that the silence is because those unfamiliar with the periodic table of elements don't get the joke.
The joke in this comic is pretty self-explanatory, especially given that the title text continues the trend in early xkcd comics of explaining the joke. Tin is a metallic element whose abbreviation on the periodic table is "Sn" (as the Latin word for tin is "stannum"). Thus, the apple is a "Sn-apple."
Snapple is a brand of beverages -- mostly bottled juices and teas -- whose name is based on a carbonated apple juice they once produced ("snappy apple").
James (in the caption) presumably once made a joke to Randall about tin or Snapple or both.
[Above the frame:] This one is entirely James' fault.
[Two Cueball-like guys are standing and talking.] Cueball: Here, take a bite of this Snapple. Friend: food!
[Cueball's friend takes a bite.] Friend: Ow!  What is this? Clink
[The panel switches to Cueball.] Cueball: It's an apple infused with tin.
[Beat panel. A wide shot of the two.]
[Same scene, except the panel is lightly shaded and the is a box above saying:] Those of you who know your periodic table should be laughing right about now.


George Clinton

Explanation:
George Clinton is an American musician most famous for his funk music and wild hair style.
His recorded music features themes of space, sci-fi, technology, and futurism. An example of his work most appropriate to this comic is the song "Mathematics" from the 1996 album T.A.P.O.A.F.O.M. (The awesome power of a fully operational mothership).
"I count the moments we're apart. And add them up mathematically and multiply them by the kisses supposedly I've been missing. Divided by the attention not to mention the affection. Subtract that from your gross potential and see I ain't missin' none. Cause any percentage of you is as good the whole pie. Any fractions thereof brings dividends of interest. Any percentage of you is as good as the whole pie. Any fractions thereof brings dividends of love. I take the square root and get boxed in every time. When I know the shortest distance between two points is in a straight line. I'ma go into you, I'ma come into you two times, and carry the fun over the one to where we equal one.” (Chorus 2x)
As Randall says, he had attempted to spread around an urban legend that George Clinton had a Bachelor of Arts degree in mathematics. However, the more Randall thought about this rumor, the more he found himself believing it was true. This behavior is related to pseudologia fantastica , which is more commonly known as pathological or compulsive lying. This comic references the associated behavior that an "individual may be aware they are lying, or may believe they are telling the truth, being unaware that they are relating fantasies." These individuals may eventually stop the lie as demonstrated by the title text, which indicates that at some later time, the individual realized that the rumor was not true, but wishes it to be so.
This may also be a reference to James Thurber's 13 clocks, in which a character called the Golux has the following exchange with the main character:
"When I was young I told a tale of buried gold, and men from leagues around dug in the woods. I dug myself." "But why?" "I thought the tale of treasure might be true." "You said you made it up." "I know I did, but I didn't know I had. I forget things, too."
The equations on the board are laplace transforms of functions.
[George Clinton uses a baton to point to the bottom of two equations on a blackboard. There is one more equation and a diagram on another blackboard to the right, which is cut off. There is text above:] I once tried to start the urban legend that George Clinton has a B.A. in mathematics
[On the left blackboard there are two formulas:] L(F(t) = F(s) = ∫ ∞ 0 f(t)e -st dt
L -1 (F(s)) = f(t) = ∫ ∞ 0 F(t)e st dt
[On the right blackboard there is part of a formula and a diagram with an x-y scale and three other lines touching down to the base. Above these lines are some numbers that are partly indecipherable.] γ n = 2 n/12 K
0 2 3 ⌊⌊⌊⌊
[Below George and the blackboards is text:] ...but I wanted it to be true so badly that I started believing it myself.


Ferret

Explanation:
Cueball 's (Cueball-like) friend makes fun of his imagination that involves a flying ferret, and then suggests to go play video games instead. This shows the irony of his definition of "imagination."  He makes fun of Cueball's creative fantasy while instead opting for a mass-produced fantasy.
The fact that Cueball lies about his goal could be a commentary on abandoning dreams to avoid confronting societal expectations.
The title text refers to the fact that Randall's brother in real life had such a pet ferret. Originally, Randall drew this comic while the ferret was still alive, and then it passed away in between his posting it on LiveJournal and reposting it with a title text on the new xkcd site. He now wishes that it will rest in peace.
The ferret returns in 31: Barrel - Part 5 and did in this way become part of the Barrel series . This has also been canonized by Randall as can be seen on this web-archive version of xkcd: The Boy and his Barrel .
The full series can be found here . But below they are listed in the order Randall has put them in his collection linked to above:
[A color drawing of a ferret with airplane wings and tail on it.]
[Cueball and his Cueball-like friend (to the left) are talking.] Friend: Why on earth did you make those wings? You don't seriously think they could let your ferret fly, right? Cueball: I... of course not.
[They continue to talk.] Cueball: That would be pretty dumb. It's just, uh... ...a Halloween costume. Friend: oh, okay.
[They continue to talk. The head of the ferret can be seen to the far right on a table.] Friend: Besides, who would want a pet to fly anyway? Cueball: Yeah. Pretty lame, huh?
[The friend leaves the frame while Cueball stays. The ferret cannot be seen.] Friend: Anyway, let's go play video games.
[Cueball stands behind after his friend has left. He looks back towards his ferret.]
[Cueball imagines his ferret flying over the ocean near the beach using his makeshift wings while holding his ferret.]


Kepler

Explanation:
A Cueball-like guy asks Cueball , the store manager, how they keep the store so clean, and he is told that they have hired Kepler, a hard worker who doesn't mind the monotony and sweeps out the same area every night.
Johannes Kepler was a German mathematician, astronomer, and astrologer, best known for his laws of planetary motion. By using Tycho Brahe 's observations of our solar system (Brahe gave Kepler the job of observing and explaining the motion of the planet Mars), Kepler was able to deduce that planets in the system do not move in a circular orbit around the Sun, but rather in an elliptical one.
In doing so, he directly contradicted Brahe's own conviction that the Earth was the centre of the universe.
According to Kepler's Second Law , "A line joining a planet and the Sun sweeps out equal areas during equal intervals of time," somewhat akin to sweeping a broom over the floor.
In the comic, the janitor Kepler also sweeps the same area, although in this case, "area" is used in the sense of "surface" (of floor) rather than in the purely mathematical sense. It is also very monotonous, like a planet's set orbit, but Kepler doesn't mind this.
The comic could also be seen as a subtle reference to the Kepler space telescope that was searching for exoplanets (planets outside the Solar system) from March 2009 to August 2013, by looking at exactly the same spot in the night sky over and over again.  Even though the telescope was not launched until 4 years after this comic was published, the details of Project Kepler had been disclosed by NASA press releases as early as 2001 .
The title text assumes that the reader is scientifically illiterate and won't understand the joke, which is ironic, considering how xkcd came to be known for embracing STEM fields and nerdiness in general.
[Two Cueball-like guys stand in an aisle in a store.] Cueball: Nice store. How do you keep the floors so clean? Store manager: Oh, we hired this dude named Kepler, he's really good. Hard worker. Doesn't mind the monotony. Sweeps out the same area every night.


Barrel - Part 3

Explanation:
In the first two comics in the Barrel series, the boy is floating in the ocean in a barrel, making fairly innocent points about life's uncertainty. In this comic, the view has zoomed out considerably, and the boy is seen to be on the edge of a gigantic whirlpool . Thus, there is now a palpably heightened sense of danger, though the boy's reaction continues to be innocent wonder.
The comic's visual composition is reminiscent of a classic 1919 illustration by Harry Clarke , made for Edgar Allan Poe 's 1841 short story " A Descent into the Maelström ." In the short story, the main character escapes from drowning by using a barrel to escape The Maelström.
This is the third in a six-part series of comics whose parts were randomly published during the first several dozen strips. The series features a character who is not consistent with what would quickly become the xkcd stick figure style. The character is in a barrel.
After Randall released the full The Boy and his Barrel story on xkcd, it has been clear that the original Ferret story should also be included as part of the barrel series.
The full series can be found here . But below they are listed in the order Randall has put them in his collection linked to above:
[A large and deep vortex is in the center; spinning water covers the whole panel. A boy in a floating barrel is near the edge, apparently about to be sucked in.] Boy: wow!


T-shirts

Explanation:
This comic satirizes the plethora of "snarky" phrase T-shirts that exist today. In the top-left, the character wears a typical (and real) snark shirt, "I see dumb people" (suggesting that the wearer thinks everyone else is dumb, while being a parody of the phrase "I see dead people" from the movie The Sixth Sense ). Other shirts shown also suggest that the wearer is better than everyone else, and perhaps the shirts increasingly suggest that the wearer is anti-social moving from top to bottom. Near the bottom of the screen, the T-shirts no longer attempt to be witty and simply have straightforward phrases like "go away" and "die". These are exaggerations of the message that the other more-realistic shirts broadcast.
The final three shirts are also exaggerated shirts that suggest Randall 's view that people who wear snarky shirts are overcompensating for the fact that they are already alone or perhaps putting up a tough exterior to conceal their sadness that no one would talk to them anyway. Most notably "maybe if this T-shirt is witty enough, someone will finally love me" sums up what Randall thinks snarky shirts really say. There are shirts with this or a similar message, although it is unclear whether they were created before this comic or as a tribute to this comic.
In the title text, Randall says that it's depressing how many of the shirts in the comic actually exist in real life, further underlining the point that these shirts are overly arrogant, to the point where one might believe that Randall made them up. This highlights the inadequacy of substance within these T-shirts and the terror they invoke in Randall's mind.
[A collection of phrases on T-shirts. The first and the last on actual black T-shirts worn by the same person, whose facial expression is more sad on the last one.] I see dumb people As a matter of fact the world does revolve around me I can only please one person per day / today is not your day. You know what your problem is? You're stupid. Get a clue Do I look like a people person? Your village called / they want their idiot back Go away I hate you all Die. Help. Maybe if this T-shirt is witty enough, someone will finally love me. Oh God I'm so alone.


Godel, Escher, Kurt Halsey

Explanation:
At the time xkcd was created, Randall was working on robotics at NASA 's Langley Center. This drawing was apparently made during that period, while attending a talk that he didn't like.
The name of the comic is a portmanteau-like play on the following:
The comic is drawn in the form of a storyboard and is clearly intended to be visualized as an animated sequence.
In the first part of the comic, two people discuss the difficulty of comparing past and present generations, since the person making the comparison invariably belongs to one of the two groups.
It's unclear whether the behatted guy is Black Hat , as Randall hadn't standardized his character designs yet, though the sarcastic comment suggests that it is. If it is, then this would be his first appearance. (He also appears in 12: Poisson , but that comic was released about 3 months later, but the numbering did not follow the release day on LiveJournal when the comics were transferred to xkcd - see the trivia for that comic.) Actually due to the order of release on LiveJournal, this, being number 6, was the first releases to use both stick figures, Cueball , Black Hat and Megan , as well as Multiple Cueballs ! See the trivia below.
The assembly of text panels found in the middle of the strip is similar to 124: Blogofractal .
The philosophy of Kurt Gödel is also a theme in 468: Fetishes .
Drawn during an unending NASA lecture [Two people are talking, one in a hat.] Cueball: it's just so hard to compare kids now with kids in the past. you can't help but to belong to one group or the other.
Cueball: and of course every generation seems awful to the one before it. look at quotes from throughout history.
Hatted: yeah, and it sure would be nice to have some historical perspective on some of this stuff. I just don't know what to make of it. [Circles are appearing--maybe snow?]
Cueball: i guess you do what you can to help the people around you and hope it turns out okay.
Cueball: in the end, what else can you do?
Hatted: lead a crusade?
[We can no longer see the people, just the circles.] it's presentism, man. the idea that historical context is irrelevant, that we understand it
all that we need take no warnings from the follies of the past. that we're facing something new.
socrates couldn't imagine the internet. but people don't change. [We can start to see a darker circle in the lower right corner.]
(The borders between the three panels on this line are cracking.) have you seen those collections of historical pornography? talk about historical context.
did you know the first porn photo was bestial in. [inside a circle:] nature?
at least that stuff was out of the mainstream [each word in one circle:] no just in history
(the three panels have merged into one on each row.)
i don't know about you, but [circled] I [uncircled] never
even once seen
[The circles are highly variable in size now, and pressed up against a larger one on the right side.]
[There is mass of circles of different sizes, with some dark fissures in between, against the side of a large circle which we can see part of in the right half of the panel. They look like cells. There's a tiny square in the center of the giant cell.]
[We see only the tiny square, centered. It has a few marks inside it.]
[Closer, the square is divided into rectangles of different sizes, each of which has text in it.]
[Much closer, we can see fragments of the text. Some are sideways, some are cut off, some are too small to read.] machine language translated by principles of isomorphism it is a consequence of the Church-Turing thesis that ... but how do you select the channel you wish to se- thou ... shou ... palin ... stri ... it is a ... crab ... be obvious to one-s ... your great intellectual achievements ... Tortise. Why ... you give this old Tortise ...
[Closer still, we can just see a huge sideways s and h.]
[Those letters are faded and mixed with a faded version of the next panel.]
girls take boys away ... never be further than a phone call and a goosebumped shiver away ... drove all night listening to mix tapes ... the past is just practice [There is a heart at the bottom and, in the lower left, the name Kurt.]
[The same as the previous panel, but with the words blurred out to scribbles.]
[Jagged, shaded shapes and strands start to fall. Faint panel borders appear again. There is a person on the far right.]
(Back to three panels per row.) [Cueball and Megan are standing amid the fragments.]
Cueball: There's too much. And so little feels important.
[The jagged edge of the shaded area is encroaching on the sides of the panel.]
What do you do?
[We see them from farther away through a rough hole in the shaded area. Bits continue to fall around them.]
[They are holding hands.]
"One of a series of strips I drew during a long and boring NASA lecture. It careens wildly from intellectual to chaotic to Godel, Escher, Bach to Kurt Halsey to chaotic and sappy. The whole series is here . "


Barrel - Part 4

Explanation:
In the first three comics of the series, the character explored the ocean in a barrel and then encountered a whirlpool, all with a reaction of innocent wonder. Here, the empty barrel floating adrift, plus the title text and a previous announcement by Randall that this would be the conclusion of barrel boy's story, imply that the character's encounter with the whirlpool separated him from the barrel, and he may have come to some harm.
This is the fifth in a six-part series of comics whose parts were randomly published during the first several dozen strips. The series features a character who is not consistent with what would quickly become the xkcd stick figure style. The character was in the barrel in parts 1-3.
After Randall released the full The Boy and his Barrel story on xkcd, it has been clear that the original Ferret story should also be included as part of the barrel series.
The full series can be found here . But below they are listed in the order Randall has put them in his collection linked to above:
[The barrel is shown on a grid paper background, floating sideways and empty in a choppy sea.]
Barrel series By the way, here are all the barrel comics on a single (easily linked) page: http://www.xkcd.com/barrel.html [This is an archived version of the page. The original link is dead. This text is not included in the statement.] I cheated, and went back and lightened the gridlines in #2. It was just bothering me. I'll try not to do that much. But as I'm not destroying anyone's childhood, I don't feel like I'm really pulling a George Lucas. I mean, I'm not destroying more than one childhood. Oops.


Fourier

Explanation:
A Fourier transform is a mathematical function transformation often used in physics and engineering.
The theory is that any line graph can be represented as the sum of a bunch of sine waves of different frequencies and amplitudes. (The most obvious application is in analyzing a sound recording in terms of the different frequencies of sounds used.) So, for any line graph, you can produce another graph of the frequencies and their amplitudes. This can be done by evaluating an integral based on the function, which is referred to as "taking the Fourier transform" of the function. The form of the integral that needs to be taken is actually shown in the third line of the comic 55: Useless .
Unfortunately, Cueball has applied this "transform" to his cat. Although it seems to still be alive and possibly even unharmed, it is clearly not in its familiar shape, and it is not clear if this condition is permanent or not.
"Periodic components" in the title text refers to the spikes in the graph.  Because sine waves repeat themselves as you go along, the presence of large amounts of one particular sine wave in the Fourier transform graph (each spike) shows that the overall result (the initial graph) is likely to have parts that also repeat themselves, like a periodic function . In other words, the cat has repeating parts.
[Cueball talks on phone. A grotesque-looking cat with many sharp vertical points looks on.] Cueball: Hi, Dr. Elizabeth?  Yeah, uh ... I accidentally took the Fourier transform of my cat... Cat: Meow!


Meat Cereals

Explanation:
Randall parodies several real-world breakfast cereals (which typically consist solely of grains and sweet flavorings) by creating versions that contain meat (animal products). The cereals that appear to be parodied (clockwise from top-left) include Froot Loops, Rice Krispies, Honey Bunches of Oats, Apple Jacks, Frosted Flakes, and Cheerios. There does not appear to be a deeper meaning to this comic than that.
The Scrapple Jacks parody (the only slightly obscure reference) appears to be made with scrapple , which, according to Wikipedia, is a mush of pork scraps and trimmings combined with cornmeal and wheat flour, often buckwheat flour, and spices. Real Apple Jacks ran an ad campaign in the 1980s and 1990s in which an adult or authority figure tasted the cereal and declared "these don't taste like apples!", thus missing the point of why kids liked the cereal. The slogan is parodied on the Scrapple Jacks box. Randall referenced this same slogan again in " 38: Apple Jacks ".
The title text, reading, "Disgusting.", apparently reflects Randall's opinion of his own creation.
[A collection of fictional meat based cereals in bright colors with nice pictures on them.] Pork Loops Mice Krispies Hammios Frosted Bacon Flakes Scrapple Jacks Hey, these don't taste like Scrapple! Honey Bunches of Goats


Elefino

Explanation:
The basis for this fairly simple xkcd comic is the subject riddle, which is properly answered, as given in the title text: "Hell if I know." When spoken, this "correct" answer sounds like "elephino" – a portmanteau of " eleph ant" and "rh ino ." This makes it again one of the early comics where Randall explains the comic via the title text.
Instead of giving the punchline of the joke, Randall answers with the unexpected "I haven't a goddamn clue," which, while having the same meaning, ruins the joke.
Q: What do you get when you cross an Elephant with a Rhino? [Picture of elephant, mathematical addition symbol, picture of rhino, equals sign, large question mark.] A: I haven't a goddamn clue.
Found it. Pepe and Seymour Elifino ... Totally worth the 🐇 hole. Iggynelix ( talk ) 15:45, 18 April 2020 (UTC)


Hitler

Explanation:
Cueball speaks to an early version of Black Hat (with more of a top hat than his later "boater" hat style) about the Holocaust and Adolf Hitler . Hitler was the leader of Nazi Germany beginning in 1933 and starting World War II in 1939 by attacking Poland. During that war, the Germans (under Hitler's leadership) killed millions of people; most of them were Jews, but other ethnic groups, homosexuals, and the mentally disabled were all targeted as well. This has come to be known as the Holocaust.
Black Hat's comment that Hitler wanted to be a painter, but did not get into art school, is historically accurate. He applied to the Vienna Academy of Fine Arts twice. In any event, Cueball implies in the second frame that had Hitler been accepted into art school, the course of history might have changed, and the Holocaust might never have occurred. Black Hat suggests that perhaps God intentionally prevented Hitler from becoming an artist because God is an "art lover" and Hitler's art was terrible.
As with other early comics, the title text explains the comic for us: this implies that God would have preferred the Holocaust to have occurred rather than allow Hitler to make some bad paintings. Such a comment that God could be so callous would surely be offensive to many people. Cueball's reaction to this shocking statement is relatively mild and suggests that Black Hat has made such controversial statements before. He will make a similarly controversial and Nazi-related statement again in 984: Space Launch System .
The title text also informs the reader that Black Hat is based on a character named Aram from a now-defunct comic strip entitled Men in Hats . In the original quote when this comic was posted on LiveJournal (see Trivia ) Randall directed the user to a specific Men in Hats comic about parenting . Like Black Hat, Aram seems to have frequently made judgmental, insulting, or controversial comments in a very emotionless manner. Aram wore a grey (perhaps intended to be black) suit with a red bowtie and a black top hat with a white strip above the brim. Black Hat's hat clearly evolved from the top hat design later in xkcd.
This may be the comic where Black Hat truly comes into existence for the first time. He appears earlier in 12: Poisson , but that was actually first released more than a month later. Then there is also 24: Godel, Escher, Kurt Halsey , released a good month earlier. But here Black Hat does not really resemble his later appearances.
[Black Hat and Cueball are talking together in the same position in all four panels.] Cueball: Learning about the Holocaust has really shaken my belief in God.
Black Hat: You know, as a young man, Hitler was rejected from art school. Cueball: Yeah... shame he didn't get in.
Black Hat: Well, have you seen any of his paintings? They're awful . Defy all rules of composition. Cueball: What are you suggesting?
Black Hat: Maybe there is a god, but he's a real art lover. Cueball: This is why I don't go out in public with you.


Donner

Explanation:
The title text explains to the reader that the Donner party was a group of pioneers who set out west along a new route that was supposed to be easier to travel, but ultimately proved slow and treacherous. They became trapped in the Sierra Nevada mountains and many died. Low on food, many of the pioneers resorted to cannibalism, eating the bodies of party members who had already died, it is believed.
In this comic, three Donner party members arrive at Joe's restaurant, where they have ordered a table for four, as given by the fact that the maître d' knows they are the Donner party and calls for a party of four. The three decline the table since they are already full. This suggests that they just have eaten the fourth member (unknown to us) of their party after they placed the order for a table at the restaurant, but before they strolled over to it anyway.
Of course, since they are not in a survival situation in this strip, cannibalism would be completely unnecessary. However, it may be possible that they are suffering from Wendigo Psychosis . Alternatively, the Donner Dinner Party may have resorted to cannibalism because it took so long to be seated at the restaurant.
In the early days of xkcd (and days when Wikipedia was not quite in the mainstream consciousness), Randall didn't trust people to understand his comics or his references, and often explained the joke in the title text like here and for instance also in 38: Apple Jacks .
[Three people stand outside a restaurant; Megan, a man with some hair and another shorter person, probably a woman. There is a sign above the door which says "Joe's" (presumably the name of the restaurant) and a menu next to it. Outside the door, there is a maître d' with a cap behind a lectern. There is a sign on the lectern which says "Eat in".] maître d': Donner, party of four? Man: Actually, never mind. Megan: We're full.


Barrel - Part 5

Explanation:
This gives a happy ending to the Barrel series . The flying ferret is from 20: Ferret . The humor is derived from the juxtaposition of two unlike elements - in this case, the contemplative and even dark nature of the Barrel series being resolved through the timely intervention of a comical flying mammal.
Said mammal could also be interpreted as a symbol of hope and following your dreams, seeing as in its original appearance, its powers of flight were just that: a dream. However, the dream becomes reality to save a child from an endless sea of hopelessness.
The series is probably inspired by the novella The Little Prince by Antoine de Saint-Exupéry . Randall is well known to be a fan of this book.
Somewhere between the release of the first ferret comic in October 2005 and the re-release of that comic (and all the other from LiveJournal in 2005) on New Year's Day 2006 on the new xkcd site, Randall's brother's ferret died - as given by the new RIP comment in the title text. The sad comment in the title text of 25: Barrel - Part 4 , ":(", possibly implying harm to the boy, along with this RIP comment, may imply that the boy has died and joined the ferret (in flying to Heaven). However, this line of reasoning only makes sense if the ferret actually died before the release of both the Part 4 comic at the end of October and this comic, which was released in the middle of November 2005, 1½ months before the new title text was made public.
This is the last in a six-part series of comics whose parts were randomly published during the first several dozen strips. The series features a character who is not consistent with what would quickly become the xkcd stick figure style. The character was in a barrel in parts 1-3.
After Randall released the full The Boy and his Barrel story on xkcd it has been clear that the original Ferret story should also be included as part of the barrel series.
The full series can be found here . But below they are listed in the order Randall has put them in his collection, linked to above:
[A boy is grasping on to a piece of driftwood in an ocean.]
[A zoomed out view of the boy still grasping on to a piece of driftwood in the ocean.]
[A ferret with some airplane wings and an airplane tail flies above the ocean.]
[A shot of the ocean, now empty.]
[The flying ferret is carrying the boy to safety.]
[The ferret carrying the boy is now in the distance with the sun on the horizon.]


Pillar

Explanation:
Two Cueball -like guys ponder the unanswerable philosophical question of whether all people observe the universe the same, or whether, for example, what one person sees as "red" might be what another see as "green". They muse that no one really knows how anyone else sees the world.
The misdirection and punchline of the comic come when the pole-guy asks if his friend can help him down from this pole where he's been standing for the entire comic. The friend's reply indicates that he does not see a pole, proving that one person can observe the world differently than another, in this case, in a far more extreme and unexpected way than color differences.
Another interpretation of the punchline is that the friend doesn't like pole-guy's idea of questioning all of human existence and mocks that philosophy by pretending not to see that he is standing on a pole.
The concept of a philosopher on a pole is likely a reference to many " stylites " or "pillar-saints" of the late antiquity period, perhaps the first and most famous them being Simeon Stylites .
Unlike most other xkcd comics, the "panels" of this comic are not divided and are drawn within a single frame.
As noted at the title text, this comic is based on a comic drawn by Randall 's brother Doug, although Randall apparently redrew and rewrote it.
[At the top of the panel is a black frame with the following text:] This one is mostly by my little brother, Doug.
[A Cueball-like guy stands on a the top of a tall pole and talks to his Cueball-like friend on the ground. The drawing is repeated three time in the same panel, once for each comment by the two guys.] Pole-guy: The sky is so blue, and all the leaves are green. Friend: Haven't you ever wondered if we really see the same colors as everyone else? It's all perception.
Pole-guy: Well, you might as well call into question all of human experience. Who really knows what world someone else sees? Friend: Yeah, I guess.
Pole-guy: Anyway, can you help me down from this pole? Friend: What pole?
"Oops, I totally forgot to update yesterday afternoon. Well, I haven't slept, so I say it's still Friday. It's been a weird couple days and I was just thinking it was the weekend. Anyway, the first version of this strip was drawn by me and then written by Doug. I redrew/wrote it and now you are reading it! Cool, huh? Also, all the barrel strips are now here for easy linkage to people you think might like them." The link (now here above directing to a webarchive) used to direct to a collection of all six The Boy and his Barrel comics. It seems Randall had a long Friday back then. So long that he forgot to post this Friday comic before midnight. And although he still had not slept when he posted it, the time-stamp reads 7:55 AM on Saturday. This thus became the first comic to be released on a Saturday. This also happened to him the next Friday/Saturday. And then two times more before he closed LiveJournal. Since then it has not happened.


Self-reference

Explanation:
Self-reference is a situation where something (a comic, a drawing, a musical work, a novel, a mathematical theorem) refers to itself in some manner. This can be a powerful technique in art, music, mathematics, and computer science (it is the basis of recursion).
In this comic, Cueball promises not to use self-reference for humor, and then realizes after a beat panel that, since this comic is referring to the series of comics he is part of, he is using self-reference, thus breaking his promise.
Without the last panel, this comic wouldn't be funny, and therefore wouldn't break the promise about using self-reference for humor. But with it, and his realization that he is breaking his promise, it does break that promise. (Do you get it?)
The title text is just another humorous self-reference.
Self-references has been used most famously later in 688: Self-Description , but was already used in 6: Irony and also in other comics .
[Cueball is standing alone.] Cueball: I promise to never again squeeze humor out of self-reference.
[Beat panel.]
[Cueball is standing alone.] Cueball: God dammit.


Flowers

Explanation:
This is a drawing of flowers that Randall made. It seems the flowers are based on his imagination, rather than being a real species - see the original quote in the trivia section.
The title text explains that Randall originally drew the flowers in pencil on normal paper; he did not paint them. Instead, he used the invert feature of a photo-editing program to reverse it from black-on-white to white-on-black. After that, he added color to the flowers.
[A sketch of flowers, drawn in green, red, and yellow on a black background.]

"Original drawing is pencil on graph paper . Bonus points if you can identify the flowers. 'cause I sure can't."


Sheep

Explanation:
Due to Randall's vacation, he picked out comics from his old high-school notebooks. This is the second in a row. It was also released a day too late.
It is a very weird drawing, especially with the title text proclaiming that it may be the sheep that is zapping the cactus. The comic 520: Cuttlefish may be a reference to this comic.
It may also be a Pokémon reference, with the sheep being the Electric-type Mareep or its evolution Flaaffy, and the cactus being Cacnea or Cacturne.
[Caption in a black frame above the image written in normal letters not all caps:] Another from my high-school notebooks. [A sheep and a green saguaro cactus in a brown pot are linked by an arcing yellow electricity bolt.]
In the comment to the original LiveJournal post there was a user called Scott who posted this original poem:
I had a little cactus and I treasured it with pride, admiring its spines and dainty flowers. Until the day - oh tragic day! - when it was RAMIFIED, by a ram with strange psychokinetic powers.
Baaing deep, this shaman sheep came whiffling through the brambles. It gazed upon my cactus and, with yellow flash and thudrous crash, with dashing, brash, and rash panache, it blew the plant to shambles.
I was, I confess, horrified - I sat and cried my eyes out! Oh stupid sheep, satanic sheep, so wrong and rash and willful! I nursed the cactus best I could, till finally it came about. It grows apace now, once again, but all it blooms is steel wool!
[And then in another post beneath this posted four minutes after the poem at 4:57 UTC (AM?) he finished with:]
Oh God I need sleep!
If this is the Scott who is a friend of Randall, it is not entirely clear....
Mary had a little lamb She tied it to a pylon Ten thousand volt went up its a** And turned its wool to nylon.


Scientists

Explanation:
This comic plays on the type of statement that news reports often use: "in what [group of experts] are calling '[quote]'," to add more weight and credibility to their stories. In this case, Cueball is using the phrase to attempt to add gravitas to the (relatively mundane) fact that his shoes are missing and he thinks it's "pretty gay" by assigning this opinion to scientists (rather than it being, presumably, his friend's or his own opinion). The same joke is at play in the image text where a leading expert thinks the situation is "retarded."
There may be a second level to the joke: Randall was still working for NASA at the time the comic was posted, so his friends at that time would presumably include scientists and "leading experts." If his friends made fun of him for not being able to find his shoes, it would therefore be accurate to say that scientists had made those statements. However, since their being scientists is irrelevant to the legitimacy of their opinions about Randall's shoe problems, presenting their teasing as an expert opinion is humorously misleading; a similar joke is at play in 1206: Einstein .
The phrases "pretty gay" and "retarded" are infantile and offensive slang for "foolish" or "contemptible," and so they are the opposite type of speech expected of experts on news reports.  (These terms were not generally considered more than mildly offensive by most of the public at the time this comic was posted; the cultural mainstream is now typically much more critical of this type of language, and this comic would likely be heavily criticized if it were published today.)
[Cueball is staring at an empty box on the floor.] Cueball: In what scientists are calling "pretty gay", I can't find my shoes.


Hyphen

Explanation:
This is the first " My Hobby " comic in xkcd . In these comics, Randall suggests an obscure activity or pastime he enjoys that he declares as his "hobby." In the premiere "My Hobby" comic, Randall's hobby is mentally re-interpreting what people mean when they say "[adjective]-ass [noun]" by moving the hyphen to after the word "ass" instead of before.
The semi- scatological suffix "-ass" is used as an intensifier in informal US English speech, usually attached to an adjective directly modifying a noun, as in "big-ass car" or "funny-ass comedian." In this comic, Cueball is exploring the increased humor aspect of changing "-ass" from a suffix modifying the adjective, to "ass-", a prefix modifying the noun, yielding a "big ass-car" or a "funny ass-comedian," the former presumably being a large car for carrying buttocks, the latter being a humorous comedian specializing in jokes about lower backs. The prefix "ass-" may also have a negative connotation, indicating that something is disliked. An "ass-car" may be a very terrible car, for example.
Another explanation would be that, since this suffix/prefix refers to an element of human anatomy, the car would be in the shape of said anatomical piece.
Outside of North America, most English speakers use "arse" to mean the buttocks, so to them, it may sound as if Randall's talking about donkeys.
[Cueball (on the left) is talking to his Cueball-like friend (on the right) about a car (left to both of them) that resembles a Volkswagen Beetle. Above the drawing is a statement:] My hobby: whenever anyone calls something an [adjective]-ass [noun], I mentally move the hyphen one word to the right.
Cueball: Man, that's a sweet ass-car.


Apple Jacks

Explanation:
Apple Jacks is a breakfast cereal produced by Kellogg's . As the title text begins to explain, there was an ad campaign for the cereal in the 1990s that focused on someone (usually someone in authority like a parent) pointing out that Apple Jacks doesn't taste like apples, and one or more kids pointing out that it doesn't matter and that "we eat what we like."  However, instead of laughing off his dad's comment and correcting him, as in the campaign, this son responds by simply saying "fuck off, dad."
This could be a commentary on today's youth being far less respectful, as the son is playing video games and seems annoyed at being interrupted, though this does not align with Randall’s public views. It may not be the first time the father has used the line, and the son is irritated by the repetition. It could also be saying that the response in the ads is unrealistic, and this is a much more realistic response.
The same ad campaign was referenced previously in 27: Meat Cereals on a parody cereal labeled Scrapple Jacks.
Cereal advertising was again referenced in 1470: Kix .
The title text could be a reference to the fact that this comic requires explanation for those who don't know of the ad (the reason this webpage exists), or it is an addition to the joke. This is another of the early comics where Randall felt the need to explain the joke in the title text, see for instance 30: Donner .
[Cueball is standing holding a bowl in his hand. His son is sitting on the floor playing video games.] Cueball: Hey, these don't taste like apples! Son: Fuck off, Dad.


Bowl

Explanation:
The comic roughly parodies a situation in which two characters are seeing who can wait longer to get the result they want. However, in the comic, the model sailing ship is not alive and doesn't experience time (except perhaps if it absorbs water and falls apart, or beaches once the water in the bowl evaporates). The comic compares the patience of a boy with that of an inanimate object. Also, it could imply that the boy has too much time on his hands.
Like many of the earlier comics, some of this comic's humor comes from the surreality of the situation. The gravity of the boy's statement is juxtaposed with the insignificance of a child's toy floating in a bowl of water. On one level, the absurdity of this is funny in itself; on another level, the audience is invited to imagine what might possibly be going through the boy's mind to make him take this toy and bowl so seriously.
Alternatively, the comic can be taken to recognize the mortality and ultimate fate of death/decay for both the boat and the boy, creating a grim moral. But, if one goes deeper into meaning, one could realize that the comic itself is humorous for trying to make a fatalistic statement using a boy and a toy boat, still making the comic ultimately humorous.
In the original quote for this comic (see trivia ), Randall states that this is not the barrel boy . This is not only because they have a similar hairstyle. Since the Barrel Boy was floating on the water in a barrel, and this boy is looking into a bowl (not barrel) filled with water, it would be easy to draw some parallels. It was obviously important for Randall to make clear that there were no such connections.
[A boy is glaring at a model sailing ship floating in a bowl of water.] Boy: Sooner or later, my friend, one of us will run out of time.
"This is not the barrel boy. Current Mood: Final Exam-y "
Announcement "What with winter break starting and the like, I'll probably be going off my regular update schedule. I'll try to post something here and there, and might end up doing more drawings than I expect, but won't stick to the MWF schedule. Thanks for the support! This has been and will continue to be a lot of fun." This may also be due to his examinations coming up. But probably he was using a lot of time preparing for the release of his new xkcd site after new year.


Light

Explanation:
Lighthouses were built on coasts to give ships a point of reference where land was, so that they could find where they were going, and to know where they should avoid during a storm. Megan fills this role for Cueball . She is his lighthouse to know where he can be safe.
This also has a romantic notion, as Megan is lighting up the world for Cueball to find her.
[A crowd of figures stand around in the dark. A Megan is illuminated by a beam of light.] In a dark and confusing world, you burn brightly I never feel lost


Old Drawing

Explanation:
This comic plays off the pun between stumped , meaning confused or at a loss, and a stump , which is the remnants of a tree that has been cut down.
Anyone snooping into his journal would be punished by such a terrible pun. The pun is so terrible that even Randall does not want to talk about it, as he mentioned in the title text.
[A tree holding a chainsaw over a recently cut-down tree. The first text is in a frame at the top of the panel.] I found this in one of my high-school notebooks. I think I drew it just to take revenge on people snooping through my stuff. Tree stump: Well, you stumped me...


Geico

Explanation:
This comic references a long-running ad campaign for Geico insurance in which a character (different in each commercial) lists a series of horrible events or news, but then caps it off with "but I've got good news: I just saved a bunch of money on my car insurance by switching to Geico" – news that may be good, but is usually either trivial compared to the magnitude of the preceding bad news, or else is said to the person whom all of the preceding bad news applied to, giving them false hope that the good news was for them. It became a recognizable pop culture phrase. Geico's ad is also mentioned in 870: Advertising .
In this one-panel comic, Cueball parodies the punchline by saving money on his car insurance by intimidation, instead of choosing the best provider.
In the title text, Randall attributes this comic to the unknown friend David . He does the same in 51: Malaria and 100: Family Circus . We can assume (or rather, we can hope ) that "this" refers to the act of writing the comic, as opposed to the act of threatening his insurance agent.
A golf club is also mentioned, and used for similarly socially unacceptable actions, in 81: Attention, shopper .
[Cueball holding a golf club.] Cueball: I just saved a bunch of money on my car insurance by threatening my agent with a golf club.


Red Spiders 2

Explanation:
This is the second published comic in the red spiders story arc, published just over 2 months after the first one . Like its predecessor, it is more of a sketch than a comic. The titular spiders appear to be ascending —or possibly building— a structure, probably to get into the window at the top of the picture. Two spiders at the top appear to be passing a block between them, implying that they are, at least, trying to change the structure.
According to the title text, it was drawn years before the previous Red Spiders .
The full series of Red Spiders comics:
[Nine red spiders, with round appendages at the end of each of their six legs, are seen navigating an environment of blocks and other geometric constructions. The second-from-the-top spider appears to be holding a block down for the spider just below to climb on to help it up, or they might be lifting the block together. One is almost outside the frame at the top.]


Love

Explanation:
This comic expresses the view of a love that is unbalanced and unequal. And how one form of love can be painful when closely examined.
It is customary for people in a romantic relationship, when one makes a declaration of love or affection, for the other to make a matching declaration. However, instead of continuing Cueball 's escalation by saying the expected response "I love you more!", Megan stops and agrees with him: he does love her more than she loves him. This leads to an uncomfortable dynamic in the relationship. The final frame shows the couple standing in silence.
In the title text, Randall expresses how this comic is shockingly stark in its portrayal of love.
[Cueball and Megan stand facing one another.] Cueball: I love you! Megan: I love you!
[Same scene as before.] Cueball: I love you more! Megan: Yeah.
[Beat panel.]


Schrodinger

Explanation:
This comic is a joke creating a humorously false synthesis, combining the principles of quantum superposition and the effects of reading a comic one panel at a time.
Schrödinger's cat is a thought experiment that illuminates the notion that a particle only resolves itself to its state upon observation, and until such observation is made, it is in all of its possible states simultaneously. In the thought experiment, a cat is both dead and alive until observation; likewise, in this comic, Black Hat and Cueball are likening the last panel to the box with the cat: until you read it, it is in a mixed state (a superposition) of both funny and unfunny.
Finally, in the last panel, both of them say "Shit." The joke is that after reading the last panel, the comic is both funny (as it is unexpected) and not funny (as the last line was a non sequitur and therefore there is no climax) at the same time, thus proving Black Hat and Cueball wrong, hence them expressing discontent with the word "shit."
The title text , which Randall here calls the alt-text, suggests that the alt text did not exist until the mouse over action occurred. This is another reference to Schrödinger's cat. You do not know if there is a title text until you mouse over, so before you mouse over, the title text could be missing or existent.
Schrödinger's cat is a famous thought experiment proposed by Erwin Schrödinger to question the Copenhagen interpretation of quantum mechanics.
Under the Copenhagen interpretation , any particle is described by a wave function that allows one to calculate the probability that it is any given state. A radioactive nucleus with a half-life of one hour, for instance, would have a wave-function that would split, showing two distinct states (decayed, undecayed) that change over time until some "observation" forced the wave-function into one state or another (called "collapsing the wave-function"). Before the wave-function is collapsed, it is incorrect to say that the atom has decayed or has not decayed; it is in a "superposition" of states, effectively both decayed and undecayed.
Schrödinger thought that the Copenhagen interpretation was absurd, and devised the below thought experiment to show this. The experiment goes as follows: Put a cat in a box, he said, with a device triggered by the decay of an atom with a half-life of one hour that would release a poisonous gas if triggered. Then, after waiting an hour, the Copenhagen interpretation would say that the atom is in a superposition of decayed and undecayed states, and thus, by extension, the cat would be in a superposition of alive and dead states. Only when the box is opened would the wave-function for the cat collapse into either alive or dead states. This thought experiment is not meant to be taken literally, as every interaction of a particle with another constitutes an observation, and many particles must interact for a cat to die, but still his argument was that since it is absurd for a cat to be both alive and dead, it is absurd for an atom to be both decayed and undecayed.
If this experiment were to be performed, the cat would not be both dead and alive.
[Black Hat and Cueball are standing next to each other. Above them the text is written in a box with shades around it.] Schrödinger's Comic
[Black Hat and Cueball are still standing next to each other, but Cueball has lifted his arms above his head. The text is again written in a box with shades around it.] The last panel of this comic is both funny and not funny at the same time.
[Black Hat and Cueball are still standing next to each other, Cueball arms are down again. The text is again written in a box with shades around it.] Until you read it, there's no way to tell which it will end up being.
[Black Hat and Cueball are still standing next to each other. Cueball has become smaller and smaller through the three frames after the first. Quite clearly here in the last panel. The text is again written in a box with shades around it.] Shit.


Secrets

Explanation:
This comic addresses the issue of commitment-phobic partners who get into relationships but get cold feet when it starts to get serious. The girl wants someone who can see every part of who she is and still love her.
In the title text, Randall mentions that he is a big fan of Kurt Halsey , a comic artist from Oregon. His style is similar to that in this comic. Many of his comics and paintings depict a couple and convey various emotions they go through, as does this comic.
In the original Randall quote (see trivia ), he gives the above link to the official home page of Kurt Halsey. Then he mentions that if you had not realized he was a big fan already, you should reconsider clicking on the link because it's depressing how much better at this he is than me .
[Drawing of a lonely girl staring down with almost closed eyes. The first line of text stands next to her to the left. The last part bottom, right.] I just want you to share in my secrets and not run away
Kurt Halsey was also referenced in 24: Godel, Escher, Kurt Halsey .


Counter-Red Spiders

Explanation:
In previous comics, red spiders are seen navigating similar landscapes. Here, humanoid stick figures are standing on top of each other to reach some place above the top of the comic, in a similar manner to how the red spiders navigate. These stick figures must be extremely light, or gravity must be really weak there, because it is extremely unlikely or even impossible to have a stack of humans that tall.
The full series of Red Spiders comics:
[A stack of stick figures, standing on each others shoulders, extends from the bottom of the frame to the top. Cuboids hang in the air.] The counter-red-spider offensive begins...


Found

Explanation:
Cueball and Megan are standing together in the middle of a simple maze. As indicated by the words in the comic, they have simply found each other, implying that there is no relationship between them other than running into each other.
As indicated in the title text, there is nothing else to say about how they met.
[Cueball and Megan are standing on a white hill (presumably snow) with a grey sky covered with thick streaks of white, and small pink dots. All letters are written in lower case.] we are just two people who found each other


Want

Explanation:
Cueball is making an honest profession of his feelings. This is often held up as a valuable thing in cementing a relationship. In the first three panels, he makes the kind of cliched poetic, romantic statements that would typically be expected. In the last panel, however, he undercuts all of this by crassly revealing that he also really wants to have sex with his paramour's sister.
In the title text, he attempts to excuse his statement by reasoning that the sister is very attractive.
[Cueball is standing talking in the same position in all four panels. In the second panel, Cueball seems to have hair.] Cueball: I want to be brave enough to tell you how I feel.
Cueball: I want to say "I love you" before I hang up the phone for once.
Cueball: I want to drive all night with you, listening to mix tapes, not caring where we end up.
Cueball: Oh, and I also really want to get with your sister. Cueball: I mean, DAMN.


Penny Arcade

Explanation:
Penny Arcade is a popular web comic that focuses on video game culture. The character above is Tycho Brahe, one of the two main characters of Penny Arcade (the other being Jonathan "Gabe" Gabriel). Penny Arcade has a reputation for making obscure references to video games without explaining, expecting the reader to be as well-versed in gaming culture as they are, represented by the attitude shown in this comic.
'Seiken Densetsu,' as mentioned in the strip, probably refers to Seiken Densetsu 3 , an Action role-playing game (Action-RPG) released for the Super Nintendo Entertainment System (SNES) in Japan in 1995. The game was neither released in the North American region nor officially translated to English for more than thirteen years after this strip. However, many North American game players might have recognized Seiken Densetsu 2 , the predecessor in the series, by its North American name: Secret of Mana .
As the title text admits, they know they behave like this, and have this reputation, but they don't care, and even refer to it in their own comic.
[A color drawing of Tycho, a man with wild brown hair in blue and cyan colored shirt. He has a big open mouth and holds one arm up while the other may be in his (unseen) pocket. He has two speech bubbles,] Tycho: You know what? If you've never played the 1995 SNES RPG " Seiken Densetsu ", don't even bother reading today's strip. Tycho: We don't need your kind here.


Malaria

Explanation:
This comic humorously considers pox parties as a means of preventing malaria. In these "parties," adults bring their children to deliberately expose them to a communicable disease to promote immunity . This is commonly done for a childhood disease like chickenpox and measles instead of vaccination.
In this comic, we see four Cueball -like children in party hats with a balloon lying on the ground, suggesting a missing "celebrant."
Some illnesses are more serious for adults than children. For example, chickenpox is far less severe contracted as a child than as an adult, the latter sometimes ending in sterility, brain damage, or worse. (Note that shingles is not adult-onset chickenpox, but a condition occasionally developed by older people who previously had chickenpox.)  Having caught chickenpox once, a person's immune system has developed antibodies , reducing vulnerability to the virus. The antibodies create immunity for a significant period of time, possibly life. However, immunity through antibody creation is not usually an effective strategy against malaria. Contrarily, once one has suffered from malaria, it can recur on its own, even after apparent healing from symptoms. Thus, having a malaria party would not be a useful exercise, as many could suffer significant illness and die.
The title text blames "David" for the party, referencing the idea of children blaming each other for an idea that turns out poorly. A malaria party is likely to have more severe consequences than, for instance, a group of 10 year olds building a ski ramp in the backyard.
Also it could be a reference to the Bible: when King David has to choose between three Threads, he chooses a disease for the whole people, lasting 3 days.
Malaria is a Mosquito-borne disease of humans and other animals caused by protists (a type of microorganism) of the genus Plasmodium . It begins with a bite from an infected female mosquito , which introduces the protists via its saliva into the circulatory system, and ultimately to the liver where they mature and reproduce. The disease causes symptoms that typically include fever and headache, which in severe cases can progress to coma or death.
At the end of the 1990s, a study reported what would turn out to be made-up health threats from MMR- vaccines , which created an MMR vaccine controversy and lower vaccination rates, even after they were exposed as false. This made pox parties more popular as the "natural alternative." However, even usually-"harmless" diseases like measles can (rarely) have complications and side-effects, up to and including death, which are by far more common and/or more severe than the actual health risks involved in vaccination. In the past 20 years, 2 Americans died from measles, both people with compromised immune systems. Also none, or late immunization, may create an immunization gap through which nearly extinct diseases can reenter a population (see e.g. Epidemiology of measles ). If this gap can be closed (or made small enough), it is possible to make a disease extinct. This was actually successfully done with smallpox , and is now attempted with the poliovirus (Causing poliomyelitis , also known as infantile paralysis).
[Four Cueball-like children wearing party hats, a discarded balloon is lying to the right. There is text above:] We had a malaria party [And there is text below:] but it turned out not to be very much fun.


Secret Worlds

Explanation:
The quote written in the large white bubbles comes from The Sandman , a comic book series about dreams. Neil Gaiman is a science fiction and fantasy author who came to fame for writing The Sandman.
The interconnected bubbles represent the secret worlds of different people and how they are connected. They may have the second meaning of the neurons in our brain.
The title text indicates that Randall used the Four color theorem , which states that a graph drawn on a flat plane (like this one) requires at most four colors so that each region differs from all of its neighbors. The comic uses four colors (red, yellow, green, blue). This clearly does not include the white bubbles with text.
Here is the quote, to those wondering how to read the comic:
“Everybody has a secret world inside of them... All of the people in the whole world, I mean everybody — no matter how dull and boring they are on the outside. Inside them they've all got unimaginable, magnificent, wonderful, stupid, amazing worlds... Not just one world. Hundreds of them. Thousands, maybe.”
Neil Gaiman, A Game of You
[A multitude of circles connected with several lines. Most of them are rather small and colored red, yellow, green and blue. Nine of them are white, six of these are larger than all the other circles, but one is the same size as the largest colored (green) circle, and the two smallest are smaller than a few of the colored circles. Pieces of text are written in all the white circles. Although it can be confusing at first, the reading order is still the normal one: left to right and top to bottom. Reading the circles in that order gives the following text:] "Everybody has a secret world inside of them. All of the people in the whole world I mean everybody No matter how dull and boring they are on the outside Inside they've all got unimaginable magnificent, wonderful, stupid, amazing, worlds Not just one world. Hundreds of them. Thousands, maybe." --Neil Gaiman Sandman


Hobby

Explanation:
This is the second in the " My Hobby " series of xkcd comics.
This comic humorously compares the rules of light gun cabinet arcade video games with real life.
Randall suggests that his hobby is going to drug busts with the expressed purpose of getting shot as an innocent bystander, thereby causing the police to lose 100 points.
Drug busts are events where police attempt to catch drug dealers, suppliers, and financiers in situations with enough evidence to convict them. In the style of arcade video games being examined, drug busts are usually depicted as chaotic events with villains, innocent bystanders, captives, and allies popping up like spring loaded targets at a shooting range in a setting with lots of places to hide.  If you don't shoot a hostile target sufficiently quickly, you will be shot, so it is common to shoot the wrong targets. To add extra challenge, these games often deduct points — or worse, cause damage to the player character — if the player shoots the wrong target. This is often frustrating; not only does the player feel that they have failed to judge their target properly, but the wasted time can cause them to get shot by the real targets.
Obviously, doing this in real life would be a really bad idea, as the hobbyist would quickly be killed. Whether this can even be a hobby is questionable because hobbies typically refer to actions that one does repeatedly, but if one was killed the first time, one would not be able to sneak into drug busts and startle police officers again. Also, if Randall actually did this, he would be dead and therefore unable to draw a comic about it. [ citation needed ]
The title text refers to the game Area 51 , which was a popular shooter arcade game from 1995 (although a console/PC game of the same name was released in 2005). Area 51 was one of many cabinet arcade games that featured a light gun that allowed players to aim at the screen and shoot in a realistic control mechanic. The title text confirms that the comic is referring to these light gun cabinet games specifically.
The title text of 188: Reload references this strip.
[A person with hair lies on the ground in a pool of red blood. At the top of the panel there is a caption. Then a text. And above the person there is a score with small lines around to indicate that it has just appeared over the body.] My hobby: When the police bust drug hideouts, I sneak in and hide. Then I jump out and startle them into shooting me so they lose points. -100
"I'm reminded of Area 51 where you accidently kept shooting the cops in the back...over and over again. Brilliant." Randall made the following reply: "That was actually precisely the game I was thinking of. I remember my brother playing that game all day at the arcade when we were little. Fuckin' innocents." This comment is reflected in the title text on xkcd.


Science

Explanation:
The solid line represents the theoretical radiation for a blackbody at 2.73 K according to Planck's Law (derived as early as 1900 by Max Planck ). The formula, almost as written in the graph, can be found here . The only changes are that on Wikipedia, the frequency f is represented by the Greek letter ν (nu) and the temperature T is included as an independent variable, so I ( f ) becomes I ( v , T ). However, I ( v , T ) still represents the spectral radiance (similar to energy density). In this formula, h is the Planck constant, c is the speed of light in a vacuum, and k is the Boltzmann constant. The frequency ( f or v ) along the x -axis is measured in gigahertz . The curve peaks at 160.4 GHz. There is no scale or unit on the energy density on the y -axis.
The theory is that the blackbody in question was the universe at the point when it had cooled down enough to allow photons to escape , 0.38 million years into its 13.8 billion years history. The photons that reach us today are the ones that have been travelling to us at lightspeed since then. As the light from astronomical objects suffers from redshift due to the expansion of the universe, and this shift becomes more pronounced with distance from the observer, this light displays in the infrared range.
The title text praises viewers who can identify where this equation and corresponding graph come from (without consulting this wiki, of course).
This comic was made into a T-shirt, but is no longer available.
On the xkcd store, there was both an explanation for the title:
And specifically an explanation for the graph:
The above is a direct copy paste, with errors. The current wiki page of the COBE mission can be found at Cosmic Background Explorer on Wikipedia .
[A graph with a curve that begins at zero, then peaks at a given frequency, indicated via a thin vertical line, and then fades down towards zero. It is possible to see the data points, which fit the curve perfectly. The y-axis is labelled. Along the x-axis, the zero point and the frequency where the peak has its maximum are labelled and close to the arrow the unit of this axis is written.] y-axis: Energy Density Along the x-axis: 0 160.4 GHz [Above the graph to the right is the following formula, with the last inner parentheses only included to make the formula clear, since in the drawing the fractions are written above and below horizontal lines:] I(f) = (2hf 3 /c 2 )(1/(e hf/kT -1)) [Below the graph is written the following:] Science. It works, bitches.


Useless

Explanation:
Randall is attempting to apply mathematics to the concept of love to no avail. Specifically, he is attempting his "normal approach", which is a term used in mathematics for the method one typically uses to solve a certain type of problem. However, as love is not a well-defined mathematical entity, his normal approach is useless. Simply put: he's saying he has found no way of describing love using only the tools of mathematics.
From the top, moving left to right, he tries the square root of love, the cosine of love, and the derivative of love with respect to x. He then attempts to left-multiply love by a 2x2 identity matrix , and finally he defines a function of love as a Fourier transform . These are all "normal approaches" to solving certain math problems.
The message of the comic is that for someone who uses math to solve all their problems, defining love is impossible.  It also indicates that love is not always a rational (or irrational) phenomenon.
This comic has been made into a t-shirt in the xkcd store, with a Laplace transform in place of the bottom integral.
Note: The Wikipedia links will provide far more detailed explanations of the mathematics.
[Different mathematical equations, all with a heart on left side, and all ending up with question marks.] √♥ = ? cos ♥ = ? d/dx ♥ = ? [1 0]♥ = ? [0 1] F{♥} = 1/√2π ∫ ∞ -∞ f(t)e it♥ dt = ? [Caption below:] My normal approach is useless here.


The Cure

Explanation:
The "real face" is that of Robert Smith , best known as the singer of the musical group The Cure , hence the title.
The joke in this comic is very simple: When Robert would sing the above lines of Coldplay 's song " Clocks ", fans of his music would know the answer: he's part of The Cure.
In the title text, Randall notes that he has not tried to draw a real face in years, as he mainly does stick drawings. In that way this comic also sticks out.
[A charcoal drawing of Robert Smith's head and face.] [Caption below:] Robert Smith should do a cover of Coldplay's Clocks, so when he sings "Am I part of the cure or am I part of the disease?" we can say, "Ooh, we know this one!"


Wait For Me

Explanation:
This comic juxtaposes a familiar exchange with a surreal outcome.
Megan is returning after a short absence. Cueball reacts as if she had been gone for years, and admits to having an affair while waiting.
In this comic, a familiar exchange occurs where one person asks the other why they did not wait. The humor lies in the improbability of him falling in love and having an affair within 90 seconds, the impossibility of him having a son in that time, and the ridiculous notion that the son would now be about Megan's current age. This is of course impossible, as it would imply that Cueball experienced twenty-ish years of life in what felt like 1.5 minutes for Megan. (He might conceivably have managed to have sex in that time span, which would fit with the experience of Cueball in 1068: Swiftkey ).
Scott appears to be a friend of Randall . Comics 57 through 59 all have the title text Opening dialogue by Scott , forming a sort of informal mini-series inspired by him. They are:
As there already was a comic released on Monday that week, the first of these three was released on Tuesday, then Wednesday and Friday. This may be related to the fact that this was the first week where the comics were not also released on LiveJournal .
[Cueball and Megan stand facing one another.] Megan: Why didn't you wait for me? Cueball: I thought you were gone forever!
[Megan throws out her arms, and Cueball is looking down.] Megan: I said I'd be back in a minute! Cueball: The... the seconds went fast at first, but then they started to drag on. Cueball: She was there for me.
[Same scene as before, except Megan has her arms out less.] Megan: You had an affair in the 90 seconds I was gone?! Cueball: ...yes.
[Cueball and Megan stand facing one another in a smaller panel.] Cueball: And we had a son.
[Same scene as before.] Cueball: He'd be about your age now.