Public domain
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# Overview
Public domain comprises the body of knowledge and innovation (especially creative works such as writing, art, music, and inventions) in relation to which no person or other legal entity can establish or maintain proprietary interests within a particular legal jurisdiction. This body of information and creativity is considered to be part of a common cultural and intellectual heritage, which, in general, anyone may use or exploit, whether for commercial or non-commercial purposes. About 15 percent of all books are in the public domain, including 10 percent of all books that are still in print.
If an item ("work") is not in the public domain, it may be the result of a proprietary interest such as a copyright, patent, or other sui generis right. The extent to which members of the public may use or exploit the work is limited to the extent of the proprietary interests in the relevant legal jurisdiction. However, when the copyright, patent or other proprietary restrictions expire, the work enters the public domain and may be used by anyone for any purpose.

# No legal restriction on use
A creative work is said to be in the public domain if there are no laws which restrict its use by the public at large. For instance, a work may be in the public domain if no laws establish proprietary rights over the work, or if the work or its subject matter are specifically excluded from existing laws.
Because proprietary rights are founded in national laws, an item may be public domain in one jurisdiction but not another. For instance, some works of literature are public domain in the United States but not in the European Union and vice versa.
The underlying idea that is expressed or manifested in the creation of a work generally cannot be the subject of copyright law (see idea-expression divide). Mathematical formulae will therefore generally form part of the public domain, to the extent that their expression in the form of software is not covered by copyright; however, algorithms can be the subject of a software patent in some jurisdictions.
Works created before the existence of copyright and patent laws also form part of the public domain. The Bible and the inventions of Archimedes are in the public domain. However, copyright may exist in translations or new formulations of these works.
Although "intellectual property" laws are not designed to prevent facts from entering the public domain, collections of facts organized or presented in a creative way, such as categorized lists, may be copyrighted. Collections of data with intuitive organization, such as alphabetized directories like telephone directories, are generally not copyrightable. In some countries copyright-like rights are granted for databases, even those containing mere facts. A sui generis database rights regime is in place in the European Union.
Works of the United States Government and various other governments are excluded from copyright law and may therefore be considered to be in the public domain in their respective countries. They may also be in the public domain in other countries as well.

# Expiration
All copyrights and patents have always had a finite term, though the terms for copyrights and patents differ. When terms expire, the work or invention is released into public domain, in most countries, this is 20 years. A trademark registration may be renewed and remain in force indefinitely provided the trademark is used, but could otherwise become generic.
Copyrights are more complex than patents; generally, in current law, the copyright in a published work expires in all countries (except Colombia, Cote d'Ivoire, Guatemala, Honduras, Mexico, Samoa, and Saint Vincent and the Grenadines) when any of the following conditions are satisfied :
- The work was created and first published before January 1, 1923, or at least 95 years before January 1 of the current year, whichever is later;
- The last surviving author died at least 70 years before January 1 of the current year;
- No Berne Convention signatory has passed a perpetual copyright on the work; and
- Neither the United States nor the European Union has passed a copyright term extension since these conditions were last updated. (This must be a condition because the exact numbers in the other conditions depend on the state of the law at any given moment.)
These conditions are based on the intersection of United States and European Union copyright law, which most other Berne Convention signatories recognize.
Note that copyright term extension under U.S. tradition usually does not restore copyright to public domain works (hence the 1923 date), but European tradition does because the EU harmonization was based on the copyright term in Germany, which had already been extended to life plus 70.

## United States law
Copyright law in the United States has changed several times. Although it is held under Feist v. Rural that Congress does not have the power to re-copyright works that have fallen into the public domain, re-copyrighting has happened: "After World War I and after World War II, there were special amendments to the Copyright Act to permit for a limited time and under certain conditions the recapture of works that might have fallen into the public domain, principally by aliens of countries with which we had been at war."
Works created by an agency of the United States government are public domain at the moment of creation.  Examples include military journalism, federal court opinions (but not necessarily state court opinions), congressional committee reports, and census data. However, works created by a contractor for the government are still subject to copyright.  Even public domain documents may have their availability limited by laws limiting the spread of classified information.

### Since 1978
Before 1978, unpublished works were not covered by the federal copyright act. Rather, they were covered under (perpetual) common law copyright.  The Copyright Act of 1976, effective 1978, abolished common law copyright in the United States so that all works, published or unpublished, are now covered by federal statutory copyright. The claim that "pre-1923 works are in the public domain" is correct only for published works; unpublished works are under federal copyright for at least the life of the author plus 70 years. For a work made for hire, the copyright in a work created before 1978, but not theretofore in the public domain or registered for copyright, subsists from January 1, 1978, and endures for a term of 95 years from the year of its first publication, or a term of 120 years from the year of its creation, whichever expires first. If the work was created before 1978 but first published on or before December 31, 2002, the work is covered by federal copyright until 2047.

### 1964 to 1977
Works published with notice of copyright or registered in unpublished form prior to January 1, 1964, had to be renewed during the 28th year of their first term of copyright to maintain copyright for a full 95-year term.
Until the Berne Convention Implementation Act of 1988, the lack of a proper copyright notice would place an otherwise copyrightable work into the public domain, although for works published between January 1, 1978 and February 28, 1989, this could be prevented by registering the work with the Library of Congress within 5 years of publication. After March 1, 1989, an author's copyright in a work begins when it is fixed in a tangible form; neither publication nor registration is required, and a lack of a copyright notice does not place the work into the public domain.

### Sound recordings
Sound recordings fixed before February 15, 1972, were generally covered by common law or in some cases by statutes enacted in certain states, not by federal copyright law. The 1976 Copyright Act, effective 1978, provides federal copyright for unpublished and published sound recordings fixed on or after February 15, 1972. Recordings fixed before February 15, 1972, are still covered, to varying degrees, by common law or state statutes.  Any rights or remedies under state law for sound recordings fixed before February 15, 1972, are not annulled or limited by the 1976 Copyright Act until February 15, 2067.

### Term extensions
Critics of copyright term extensions have said that Congress has achieved a perpetual copyright term "on the installment plan."

## British law
British government works are restricted by either Crown Copyright or Parliamentary Copyright. Published Crown Copyright works become public domain at the end of the year 50 years after they were published, unless the author of the work held copyright and assigned it to the Crown. In that case, the copyright term is the usual life of author plus 70 years. Unpublished Crown Copyright documents become public domain at the end of the year 125 years after they were first created. However, under the legislation that created this rule, and abolished the traditional common law perpetual copyright of unpublished works, no unpublished works will become public domain until 50 years after the legislation came into effect. Since the legislation became law on 1 August 1989, no unpublished works will become public domain under this provision until 2039. Parliamentary Copyright documents become public domain at the end of the year 50 years after they were published. Crown Copyright is waived on some government works provided that certain conditions are met.

## Laws of Canada, Australia, and other Commonwealth nations
These numbers reflect the most recent extensions of copyright in the United States and Europe. Canada and New Zealand have not, as of 2006, passed similar twenty-year extensions. Consequently, their copyright expiry times are still life of the author plus 50 years. Australia passed a 20-year copyright extension in
2004, but delayed its effect until 2005, and did not make it revive already-expired copyrights. Hence, in Australia works by authors who died before 1955 are still in the public domain.
As a result, works ranging from Peter Pan to the stories of H. P. Lovecraft are public domain in both countries. (The copyright status of Lovecraft's work is debatable, as no copyright renewals, which were necessary under the laws of that time, have been found. Also, two competing parties have independently claimed copyright ownership on his work.)
As with most other Commonwealth of Nations countries, Canada and Australia follow the general lead of the United Kingdom on copyright of government works. Both have a version of Crown Copyright which lasts for 50 years from publication. New Zealand also has Crown Copyright, but has a much greater time length, at 100 years from the date of publication. India has a government copyright of sixty years from publication, to coincide with its somewhat unusual life of the author plus sixty years term of copyright.

## Thai law
According to Thai copyright law, the copyright term is the life of author plus 50 years. When the author is a legal entity  or an anonymous person, the copyright term is 50 years from the date of publication. Works of applied art (defined as drawings/paintings, sculpture, prints, architecture, photography, and drafts) have a copyright term of 50 years from publication. Republication of works after the expiration of the copyright term does not reset the copyright term. Thai state documents are public domain.

## Japanese law
Japanese copyright law does not mention public domain. Hence, even when some materials are said to be "in the public domain" there can be some use restrictions. In that case, the term copyright-free is sometimes used instead.
Many pre-1953 both Japanese and non-Japanese films are considered to be in the public domain in Japan.

## Examples
Examples of inventions whose patents have expired include the inventions of Thomas Edison.
Examples of works whose copyrights have expired include the works of Carlo Collodi, Mozart, and most of the works of Mark Twain, excluding the work first published in 2001, A Murder, a Mystery, and a Marriage. In the United States, the images of Frank Capra's classic film, It's a Wonderful Life (1946) entered into the public domain in 1974, because someone inadvertently failed to file a copyright renewal application with the Copyright Office during the 28th year after the film's release or publication. It wasn't until 1993 when Republic Pictures relied on the 1990 United States Supreme Court ruling in Stewart v. Abend to enforce its claim of copyright to portions of the film's sound track. As a result, only NBC is currently licensed to show the film on U.S. network television, the colourized versions have been withdrawn and Republic got exclusive video rights to the film (under license with Artisan Entertainment). Rights to It's a Wonderful Life now belong to Paramount Pictures.
Currently four shorts by the Three Stooges are in the public domain due to accidental failure to renew their copyrights in the '60s. These are Disorder in the Court, Brideless Groom, Malice in the Palace, and Sing a Song of Six Pants. Other features and films from the Stooges are known to be in public domain as well.
Several episodes of The Lucy Show are similarly in the public domain.
Some works may never fully lapse into the public domain, such as the play Peter Pan by J. M. Barrie. While the copyright of this work expired in the United Kingdom in 1987, it has been granted special treatment under the Copyright, Designs and Patents Act 1988 (Schedule 6) that requires certain royalties to be paid for performances within the UK, so long as Great Ormond Street Hospital continues to exist.  J. M. Barrie had bequeathed the rights to Peter Pan to the hospital in perpetuity as an endowment.

# Disclaimer of interest
Laws may make some types of works and inventions ineligible for monopoly; such works immediately enter the public domain upon publication. Many kinds of mental creations, such as publicized baseball statistics, are never covered by copyright. However, any special layout of baseball statistics, or the like, would be covered by copyright law. For example, while a phonebook is not covered by copyright law, any special method of laying out the information would be.
For example: U.S. copyright law, 17 U.S.C.  105, releases all works created by the U.S. government into the public domain. U.S. patent applications containing a copyright notice must also include a disclaimer of certain exclusive rights as part of the terms of granting the patent to the invention (leaving open the question regarding copyright of patents with no such notice). Agreements that Germany signed at the end of World War I released such trademarks as "aspirin" and "heroin" into the public domain in many areas.
Another example would be Charles Darwin's theory of evolution. Being an abstract idea it has therefore never been patentable. After Darwin constructed his theory, he did not disclose it for over a decade (see Development of Darwin's theory). He could have kept his manuscript in his desk drawer forever but once he published the idea, the idea itself entered public domain. However, the carrier of his ideas, in the form of a book titled The Origin of Species, was covered by copyright (though, since he died in 1882, the copyright has since expired).

## Copyright
In the past, in some jurisdictions such as the USA, a work would enter the public domain with respect to copyright if it was released without a copyright notice. This was true prior to March 1, 1989 (according to the USA Copyright office), but is no longer the case. Any work (of certain, enumerated types) receives copyright as soon as it is fixed in a tangible medium.
It is commonly believed by non-lawyers that it is impossible to put a work into the public domain. Although copyright law generally does not provide any statutory means to "abandon" copyright so that a work can enter the public domain, this does not mean that it is impossible or even difficult, only that the law is somewhat unclear. Congress may not have felt it necessary to codify this part of the law, because abandoning property (like a tract of land) to the public domain has traditionally been a matter of common law, rather than statute. (Alternatively, because copyright has traditionally been seen as a valuable right, one which required registration to achieve, it would not have made sense to contemplate someone abandoning it in 1976 and 1988.)

### Statutory law
There are several references to putting copyrighted work into the public domain. The first reference is actually in a statute passed by Congress, in the Computer Software Rental Amendments Act of 1990 (H.R. 5498 of the 101st Congress). Although most of the Act was codified into Title 17 of the U.S. Code, there is a very interesting provision relating to "public domain shareware" which was not, and is therefore often overlooked.
Sec. 105. Recordation of Shareware
(a) IN GENERAL- The Register of Copyrights is authorized, upon receipt of any document designated as pertaining to computer shareware and the fee prescribed by section 708 of title 17, United States Code, to record the document and return it with a certificate of recordation.
(b) MAINTENANCE OF RECORDS; PUBLICATION OF INFORMATION- The Register of Copyrights is authorized to maintain current, separate records relating to the recordation of documents under subsection (a), and to compile and publish at periodic intervals information relating to such recordations. Such publications shall be offered for sale to the public at prices based on the cost of reproduction and distribution.
(c) DEPOSIT OF COPIES IN LIBRARY OF CONGRESS- In the case of public domain computer shareware, at the election of the person recording a document under subsection (a), 2 complete copies of the best edition (as defined in section 101 of title 17, United States Code) of the computer shareware as embodied in machine-readable form may be deposited for the benefit of the Machine-Readable Collections Reading Room of the Library of Congress.
(d) REGULATIONS- The Register of Copyrights is authorized to establish regulations not inconsistent with law for the administration of the functions of the Register under this section. All regulations established by the Register are subject to the approval of the Librarian of Congress.
One purpose of this legislation appears to be to allow "public domain shareware" to be filed at the Library of Congress, presumably so that the shareware would be more widely disseminated. Therefore, one way to release computer software into the public domain might be to make the filing and pay the $20 fee. This could have the effect of "certifying" that the author intended to release the software into the public domain. It does not seem that registration is necessary to release the software into the public domain, because the law does not state that public domain status is conferred by registration. Judicial rulings supports this conclusion, see below.
By comparing paragraph (a) and (c), one can see that Congress distinguishes "public domain" shareware as a special kind of shareware. Because this law was passed after the Berne Convention Implementation Act of 1988, Congress was well aware that newly created computer programs (two years worth, since the Berne Act was passed) would automatically have copyright attached. Therefore, one reasonable inference is that Congress intended that authors of shareware would have the power to release their programs into the public domain. This interpretation is followed by the Copyright Office in 37 C.F.R.  201.26.
The Berne Convention Implementation Act of 1988 states in section twelve that the Act "does not provide copyright protection for any work that is in the public domain." The congressional committee report explains that this means simply that the Act does not apply retroactively. Some interest groups lobbied heavily to make the Act retroactive in order to increase the U.S.'s negotiating leverage with other countries, because the U.S. often asks developing countries to allow the copyrighting of previously public-domain work.
Although the only part of the act that does mention "public domain" does not speak to whether authors have the right to dedicate their work to the public domain, the remainder of the committee report does not say that they intended copyright should be an indestructible form of property. Rather the language speaks to getting rid of formalities in order to comply with Berne (non-compliance had become a severe impediment in trade negotiations) and making registration and marking optional, but encouraged. A fair reading is that the Berne Act did not intend to take away author's right to dedicate works to the public domain, which they had (by default) under the 1976 Act.
Although there is support in the statutes for allowing work to be dedicated to the public domain, there cannot be an unlimited right to dedicate work to the public domain because of a quirk of U.S. copyright law which grants the author of a work the right to cancel "the exclusive or nonexclusive grant of a transfer or license of copyright or of any right under a copyright" thirty-five years later, unless the work was originally a work for hire. 
It is unsettled how this section would mesh with a purported public domain dedication. Any of these interpretations are possible:
- No effect. Any holder of a copyright can release it to the public domain. This interpretation is probably wrong, because then an author would lose the right to his "termination right," which in practical terms means a royalty. To prevent paying the royalty, a comic book company could release the copyright to the public domain but hold onto the trademark, which would suffice to prevent knock-off comics from being made. Because the Captain America case (Marvel v. Simon) showed that this termination right cannot be alienated before death, this interpretation is almost certainly wrong.
- Some effect. An author may release his own work into the public domain, and a company holding a work for hire may release his work into the public domain. But a company which has purchased a copyright from an author (as was the case with most of the "Golden Age" comic book writers) cannot. Although the distinction of allowing an author to release his own work is not explicit in the statute, it may not be literally inconsistent (it is not a "transfer" or a "license," and it arguably is not a grant of a right under copyright), and this reading is necessary to comply with the 1990 Act discussed above, as well as the case law discussed below.
- Strong effect. Only a company holding a work for hire can release the work into the public domain. Because of the references to "shareware" (above) and "programmers" (below), and the fact that many software companies in the 1980s were quite small (and thus did not have employees), this reading seems inconsistent with the intent of Congress.

### Case law
Another form of support comes from the seminal case Computer Associates Int'l v. Altai, 982 F.2d 693. This case set the standard for determining copyright infringement of computer software and is still followed today. Moreover, it was decided by the Second Circuit appellate court, which is famous for handing down some of the most well-reasoned American copyright decisions. In this case, it discusses the public domain.
(c) Elements Taken from the Public Domain
Closely related to the non-protectability of scenes a faire, is material found in the public domain. Such material is free for the taking and cannot be appropriated by a single author even though it is included in a copyrighted work. ... We see no reason to make an exception to this rule for elements of a computer program that have entered the public domain by virtue of freely accessible program exchanges and the like. See 3 Nimmer Section 13.03  ; see also Brown Bag Software, slip op. at 3732 (affirming the district courts finding that laintiffs may not claim copyright protection of an . . . expression that is, if not standard, then commonplace in the computer software industry.). Thus, a court must also filter out this material from the allegedly infringed program before it makes the final inquiry in its substantial similarity analysis.
This decision holds that computer software may enter the public domain through "freely accessible program exchanges and the like," or by becoming "commonplace in the computer industry." Relying only on this decision, it is unclear whether an author can dedicate his work to the public domain simply by labeling it as such, or whether dedication to the public domain requires widespread dissemination.
This could make a distinction in a CyberPatrol-like case, where a software program is released, leading to litigation, and as part of a settlement the author assigns his copyright. If the author has the power to release his work into the public domain, there would be no way for the new owner to stop the circulation of the program. A court may look on an attempt to abuse the public domain in this way with disfavor, particularly if the program has not been widely disseminated. Either way, a fair reading is that an author may choose to release a computer program to the public domain if he can arrange for it to become popular and widely disseminated.

### Treatise analysis
The treatise cited (Nimmer), holds in its most recent edition:
It is axiomatic that material in the public domain is not protected by copyright, even when incorporated into a copyrighted work. ...
An enormous amount of public domain software exists in the computer industry, perhaps to a much greater extent than is true of other fields. Nationwide computer "bulletin boards" permit users to share and distribute programs. In addition, computer programming texts may contain examples of actual code that programmers are encouraged to copy.
Programmers often will build existing public domain software into their works. The courts thus must be careful to limit protection only to those elements of the program that represent the author's original work.
Although Computer Associates only mentioned the issue in passing, Nimmer observes that the public domain is particularly rich and valuable for computer programs. He seems to say that a computer program author who wishes to release his work into the public domain may either include it in a book as example code or post it on a "bulletin board" and encourage sharing and distribution. (Nimmer is the treatise most widely cited in copyright opinions, and is generally authoritative.)

## Patent
With regard to patents, on the other hand, public use or publishing the details of an invention before applying for a patent will generally place an invention in the public domain and (in theory) prevent its subsequent patenting by anyone  an effective disclaimer. For example, a chemistry journal publishing a formula prevents patenting the formula by anyone. This tactic was commonly used by Bell Labs. The famous Bell Labs Technical Journal was sent free of charge to the library of the U.S. Patent Office to establish a base of prior art without the inconvenience, cost, and hassle of filing patent applications for inventions of no immediate monetary value. (Unix was famously described in this journal.) This is sometimes called "defensive disclosure" - one way to make sure you are not later accused of infringing a patent on your own invention. There is an exception to this rule, however: in U.S. (not European) law, an inventor may file a patent claim up to one year after publishing a description (but not, of course, if someone else published or used it first).
In practice, patent examiners only consider other patents and the books they have in their library for prior art, largely because the patent office has an elaborate classification system for inventions. This means that an increasing number of issued patents may be invalid, based upon prior art that was not brought to the examiner's attention. Once a patent is issued, it is very expensive to invalidate. Publishing a description on a website as a preemptive disclosure does very little in a practical sense to release an invention to the public domain; it might still be considered "patentable", although erroneously. However, anyone aware of an omitted prior art citation in an issued patent may submit it to the US Patent Office and request a "reexamination" of the patent during the enforceable period of the patent (that is, its life plus statute of limitations). This may result in loss of some or all of the patent  on the invention, or it may backfire and actually strengthen the claims.
An applicant may also choose to file a Statutory Invention Registration, which has the same effect as a patent for prior art purposes. These SIRs are relatively expensive. These are used strategically by large companies to prevent competitors from obtaining a patent.
Section 102(c) says that an invention that has been "abandoned" cannot be patented. There is precious little case-law on this point. It is largely a dead letter.
If an inventor has an issued patent, there are several ways to release it to the public domain (other than simply letting it expire). First, he can fail to pay the maintenance fee the next time it is due, about every four years. Alternatively he can file a terminal disclaimer under 37 CFR 1.321 for a reasonable fee. The regulations explicitly say that the "patentee may disclaim or dedicate to the public the entire term, or any terminal part of the term, of the patent granted. Such disclaimer is binding upon the grantee and its successors or assigns." Usually this is used during the application process to prevent another patent from a "double patenting" invalidation. Lastly, he may grant a patent license to the world, although the issue of revocability may raise its head again.

## Trade secret
If guarded properly, trade secrets are forever. A business may keep the formula to Coca-Cola a secret. However, once it is disclosed to the public, the former secret enters public domain, although an invention using the former secret may still be patentable in the United States if it is not barred by statute (including the on-sale bar).
Some businesses choose to protect products, processes, and information by guarding them as trade secrets, rather than patenting them. Hershey Foods, Inc., for example, does not patent some of its processes, such as the recipe for Reese's, but rather maintains them as trade secrets, to prevent competitors from easily duplicating or learning from their invention disclosures.
One risk, however, is that anyone may reverse engineer a product and thus discover (and copy and publish) all of its secrets, to the extent they are not covered by other laws (e.g., patent, contract).

## Trademark
A trademark registration is renewable. If a trademark owner wishes to do so, he may maintain a registration indefinitely by paying renewal fees, using the trademark and defending the registration.
However, a trademark or brand can become unenforceable if it becomes the generic term for a particular type of product or service  a process called "genericide." If a mark undergoes genericide, people are using the term generically, not as a trademark to exclusively identify the particular source of the product or service. One famous example is "thermos" in the United States.
Because trademarks are registered with governments, some countries or trademark registries may recognize a mark, while others may have determined that it is generic and not allowable as a trademark in that registry. For example, the drug "acetylsalicylic acid" (2-acetoxybenzoic acid) is better known as aspirin in the United States  a generic term. In Canada, however, "aspirin" is still a trademark of the German company Bayer. Bayer lost the trademark after World War I, when the mark was sold to an American firm. So many copycat products entered the marketplace during the war that it was deemed generic just three years later.
Terms can be deemed "generic" in two ways. First, any potential mark can be deemed "generic" by a trademark registry, that refuses to register it. In this instance, the term has no secondary meaning that helps consumers identify the source of the product; the term serves no function as a "mark". Second, a mark, already in use, may be deemed generic by a court or registry after the mark is challenged as generic  this is known as "genericide". In this instance, the term previously had a secondary meaning, but lost its source-identifying function.
To avoid "genericide", a trademark owner must balance between trying to dominate the market, and dominating their market to such an extent that their product name defines the market. A manufacturer who invents an amazing breakthrough product which cannot be succinctly described in plain English (for example, a vacuum-insulated drinking flask) will likely find its product described by the trademark ("Thermos"). If the product continues to dominate the market, eventually the trademark will become generic ("thermos").
However, "genericide" is not an inevitable process. In the late 1980s "Nintendo" was becoming synonymous with home video game consoles but Nintendo was able to reverse this process through marketing campaigns. Xerox was also successful in avoiding its name becoming synonymous with the act of photocopying (although, in some languages (Russian) and countries (like India), it became generic).
Trademarks currently thought to be in danger of being generic include Jell-O, Band-Aid, Rollerblade, Google, Spam, Hoover, and Sheetrock. Google vigorously defends its trademark rights. Although Hormel has resigned itself to genericide , it still fights attempts by other companies to register "spam" as a trademark in relation to computer products .
When a trademark becomes generic, it is as if the mark were in the public domain.
Trademarks which have been genericized in particular places include: Escalator, Trampoline, Raisin Bran, Linoleum, Dry Ice, Shredded Wheat (generic in US), Mimeograph, Yo-Yo, Kerosene, Cornflakes, Cube Steak, Lanolin, and High Octane, (Source: Xerox ad, reprinted in Copyright, Patent, Trademark, ..., by Paul Goldstein, 5th ed., p. 245) as well as Aspirin (generic in the United States, but not in Canada), Allen wrench, Beaver Board, Masonite, Coke, Pablum, Styrofoam, Heroin, Bikini, Chyron, Weedwhacker, Kleenex, Linux (generic in Australia) and Zipper.

## Domain name
People may buy and sell domain names. Sometimes, people advertise them as their own "intellectual property". In early 2000, the record-breaker domain name "business.com" was sold for $8 million (this was resold in July 2007 for $345 million).
A domain name never enters public domain. If nobody owns it, it simply doesn't exist. Top level domains, such as .com, are controlled by the ICANN (Internet Corporation for Assigned Names and Numbers). A domain name is sometimes described as a lease, but this has only a shred of truth in it. In fact it is much closer to a trademark. While a leaseholder of, say, real estate cannot be ejected from the property by anybody (except the government, in rare cases), domain names are subject to cybersquatting suits and trademark suits.

# Public domain and the Internet
The term "public domain" is often poorly understood and has created significant legal controversy. Historically, most parties attempting to address public domain issues fell into two camps:
- Businesses and organizations who could devote staff to resolving legal conflicts through negotiation and the court system.
- Individuals and organizations using materials covered by the fair use doctrine, reducing the need for substantial governmental or corporate resources to track down individual offenders.
With the advent of the Internet, however, it became possible for anybody with access to this worldwide network to "post" copyrighted or otherwise-licensed materials freely and easily. This aggravated an already established but false belief that if something is available through a free source, it must be public domain. Once such material was available on the net, it could be perfectly copied among thousands or even millions of computers very quickly and essentially without cost.

## Freely obtained does not mean free to republish
These factors have reinforced the false notion that "freely obtained" means "public domain." One could argue that the Internet is a publicly-available domain, not licensed or controlled by any individual, company, or government; therefore, everything on the Internet is public domain. This specious argument ignores the fact that licensing rights are not dependent on the means of distribution or consumer acquisition. (If someone gives a person stolen merchandise, it is still stolen, even if the receiving party was not aware of it.) Chasing down copyright violations based on the idea that information is inherently free has become a primary focus of industries whose financial structure is based on their control of the distribution of such media.

## (Almost) everything written down is copyrighted
Another complication is that publishing exclusively on the Internet has become extremely popular. In countries party to the Berne Convention, an author's original works are covered by copyright as soon as the work is put into a "fixed" form; no formal copyright notice or registration is necessary. But such laws were passed at a time when the focus was on materials that could not be as easily and cheaply reproduced as digital media, nor did they comprehend the ultimate impossibility of determining which set of electronic bits is original. Technically, any Internet posting (such as blogs or emails) could be considered copyrighted material unless explicitly stated otherwise.
The distribution of many types of Internet postings (particularly Usenet articles and messages sent to electronic mailing lists) inherently involves duplication. The act of posting such a work can therefore be taken to imply consent to a certain amount of copying, as dictated by the technical details of the manner of distribution. However, it does not necessarily imply total waiver of copyright.

## Furthering the public domain with the Internet
Many people are using the Internet to contribute to the public domain, or make works in the public domain more accessible to more people. For example, Project Gutenberg and LibriVox coordinate the efforts of people who transcribe works in the public domain into electronic form. Some projects exist for the sole purpose of making material available into the public domain or under no-cost licenses. The IMSLP (International Music Score Library Project) is attempting to create a virtual library containing all public domain musical scores, as well as scores from composers who are willing to share their music with the world free of charge.
Note that there are many works that are not part of the public domain, but for which the owner of some proprietary rights has chosen not to enforce those rights, or to grant some subset of those rights to the public.
See, for example, the Free Software Foundation which creates copyrighted software and licenses it without charge to the public for most uses under a class of license called "copyleft", forbidding only proprietary redistribution. Wikipedia does much the same thing with its content under the GNU Free Documentation License. Sometimes such work is inadvertently referred to as "public domain" in colloquial speech.
Note also that while some works (especially musical works) may be in the public domain, U.S. law considers performances or (some) transcriptions of those works to be derivative works, potentially subject to their own copyrights. Similarly, a film adaptation of a public-domain story (such as a fairy tale or a classic work of literature) may itself be copyrightable.

## Kopimi
There is an established form of copyright antonym called kopimi, a wordplay on "copy me." Kopimi is not a license, it is simply a message that expresses the author's desire for people to modify and distribute the work.

## Media in the public domain
There are hundreds of movies, cartoons and television shows that have fallen into the public domain. Some of these movies are considered classics, such as The Gold Rush (1925) starring Charlie Chaplin, A Star Is Born (1937), and Night of the Living Dead (1968). The works either did not include a proper copyright notice when published, or the copyright was not renewed and therefore the content is now in the public domain.