Query: ‘Getting hung up on the exact nature of the records is interesting, and there’s lots of technical work that can be done there, but the main take-home response there is that the trends we’ve been seeing since the 1970s are continuing and have not paused in any way,’ he said.”

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Rock music <=SEP=> Rock music is a genre of popular music that originated as `` rock and roll '' in the United States in the early 1950s , and developed into a range of different styles in the 1960s and later , particularly in the United Kingdom and the United States . It has its roots in 1940s and 1950s rock and roll , a style which drew heavily on the African-American genres of blues and rhythm and blues , and from country music . Rock music also drew strongly on a number of other genres such as electric blues and folk , and incorporated influences from jazz , classical and other musical styles . Musically , rock has centered on the electric guitar , usually as part of a rock group with electric bass and drums and one or more singers . Typically , rock is song-based music usually with a 4/4 time signature using a verse-chorus form , but the genre has become extremely diverse . Like pop music , lyrics often stress romantic love but also address a wide variety of other themes that are frequently social or political .   By the late 1960s `` classic rock '' period , a number of distinct rock music subgenres had emerged , including hybrids like blues rock , folk rock , country rock , raga rock , and jazz-rock , many of which contributed to the development of psychedelic rock , which was influenced by the countercultural psychedelic and hippie scene . New genres that emerged included progressive rock , which extended the artistic elements ; glam rock , which highlighted showmanship and visual style ; and the diverse and enduring subgenre of heavy metal , which emphasized volume , power , and speed . In the second half of the 1970s , punk rock reacted by producing stripped-down , energetic social and political critiques . Punk was an influence in the 1980s on new wave , post-punk and eventually alternative rock . From the 1990s alternative rock began to dominate rock music and break into the mainstream in the form of grunge , Britpop , and indie rock . Further fusion subgenres have since emerged , including pop punk , rap rock , and rap metal , as well as conscious attempts to revisit rock 's history , including the garage rock/post-punk and synth-pop revivals at the beginning of the 2000s ( decade ) .   Rock music has also embodied and served as the vehicle for cultural and social movements , leading to major subcultures including mods and rockers in the UK and the hippie counterculture that spread out from San Francisco in the US in the 1960s . Similarly , 1970s punk culture spawned the goth and emo subcultures . Inheriting the folk tradition of the protest song , rock music has been associated with political activism as well as changes in social attitudes to race , sex and drug use , and is often seen as an expression of youth revolt against adult consumerism and conformity .

Wayback Machine <=SEP=> The Wayback Machine is a digital archive of the World Wide Web and other information on the Internet created by the Internet Archive , a nonprofit organization , based in San Francisco , California , United States . The Internet Archive launched the Wayback Machine in October 2001 . It was set up by Brewster Kahle and Bruce Gilliat , and is maintained with content from Alexa Internet . The service enables users to see archived versions of web pages across time , which the archive calls a `` three dimensional index '' .   Since 1996 , the Wayback Machine has been archiving cached pages of websites onto its large cluster of Linux nodes . It revisits sites every few weeks or months and archives a new version . Sites can also be captured on the fly by visitors who enter the site 's URL into a search box . The intent is to capture and archive content that otherwise would be lost whenever a site is changed or closed down . The overall vision of the machine 's creators is to archive the entire Internet .   The name Wayback Machine was chosen as a reference to the `` WABAC machine '' ( pronounced way-back ) , a time-traveling device used by the characters Mr. Peabody and Sherman in The Rocky and Bullwinkle Show , an animated cartoon . In one of the animated cartoon 's component segments , Peabody 's Improbable History , the characters routinely used the machine to witness , participate in , and , more often than not , alter famous events in history .

Wikipedia <=SEP=> Wikipedia ( -LSB- wɪkiˈpiːdiə -RSB- ) is a free online encyclopedia with the aim to allow anyone to edit articles . Wikipedia is the largest and most popular general reference work on the Internet and is ranked among the ten most popular websites . Wikipedia is owned by the nonprofit Wikimedia Foundation .   Wikipedia was launched on January 15 , 2001 , by Jimmy Wales and Larry Sanger . Sanger coined Wikipedia , a portmanteau of wiki and encyclopedia . There was only the English language version initially , but it quickly developed similar versions in other languages , which differ in content and in editing practices . With articles , the English Wikipedia is the largest of the more than 290 Wikipedia encyclopedias . Overall , Wikipedia consists of more than 40 million articles in more than 250 different languages and , , it had 18 billion page views and nearly 500 million unique visitors each month .   As of March 2017 , Wikipedia has about forty thousand high-quality articles known as Featured Articles and Good Articles that cover vital topics . In 2005 , Nature published a peer review comparing 42 science articles from Encyclopædia Britannica and Wikipedia , and found that Wikipedia 's level of accuracy approached Encyclopædia Britannicas . Criticism of Wikipedia includes claims that it exhibits systemic bias , presents a mixture of `` truths , half truths , and some falsehoods '' , and that , in controversial topics , it is subject to manipulation and spin .

Twitter <=SEP=> Twitter ( -LSB- ˈtwɪtər -RSB- ) is an online news and social networking service where users post and interact with messages , `` tweets '' , restricted to 140 characters . Registered users can post tweets , but those who are unregistered can only read them . Users access Twitter through its website interface , SMS or a mobile device app . Twitter Inc. is based in San Francisco , California , United States , and has more than 25 offices around the world .   Twitter was created in March 2006 by Jack Dorsey , Noah Glass , Biz Stone , and Evan Williams and launched in July . The service rapidly gained worldwide popularity . In 2012 , more than 100 million users posted 340 million tweets a day , and the service handled an average of 1.6 billion search queries per day . In 2013 , it was one of the ten most-visited websites and has been described as `` the SMS of the Internet '' . As of 2016 , Twitter had more than 319 million monthly active users . On the day of the 2016 U.S. presidential election , Twitter proved to be the largest source of breaking news , with 40 million election-related tweets sent by 10 p.m. ( Eastern Time ) that day .