Mainstream media is a term and abbreviation used to refer collectively to the various large mass news media that influence many people, and both reflect and shape prevailing currents of thought. The term is used to contrast with alternative media which may contain content with more dissenting thought at variance with the prevailing views of mainstream sources.
The term is often used for large news conglomerates, including newspapers and broadcast media, that underwent successive mergers in many countries. The concentration of media ownership has raised concerns of a homogenization of viewpoints presented to news consumers. Consequently, the term mainstream media has been widely used in conversation and the blogosphere, sometimes in oppositional, pejorative or dismissive senses, in discussion of the mass media and media bias.
The advent of the internet allowed the expression of a more diverse or alternative viewpoint which may contrast to mainstream media, to the point where the term mainstream media is seen in pejorative terms.
Lamestream media is a common pejorative alternative. Sarah Palin referred to "lamestream media," notably around 2009 during her participation in the Tea Party Express, in the context of what she perceived as media misrepresentation of the Tea Party movement.
In the United States, movie production is known to have been dominated by major studios since the early 20th century; before that, there was a period in which Edison's Trust monopolized the industry. In the early twenty-first century the music and television industries was subject to media consolidation, with Sony Music Entertainment's parent company merging their music division with Bertelsmann AG's BMG to form Sony BMG, and Tribune's The WB and CBS Corp.'s UPN merging to form The CW. In the case of Sony BMG there existed a "Big Five", later "Big Four", of major record companies, while The CW's creation was an attempt to consolidate ratings and stand up to the "Big Four" of American network (terrestrial) television (although the CW was actually partially owned by one of the Big Four in CBS). In television, the vast majority of broadcast and basic cable networks, over a hundred in all, are controlled by eight corporations: Fox Corporation, The Walt Disney Company (which includes the ABC, ESPN, FX and Disney brands), National Amusements (which owns ViacomCBS), Comcast (which owns NBCUniversal), AT&T (which owns WarnerMedia), Discovery, Inc., E. W. Scripps Company, Altice USA, or some combination thereof.
Media mergers and concentration in the United States
Over time the rate of media mergers has increased, while the number of media outlets has also increased. This has resulted in a higher concentration of media ownership, with fewer companies owning more media outlets.
Some critics, such as Ben Bagdikian, assailed concentration of ownership, arguing that large media acquisitions limit the information accessible to the public. Other commentators, such as Ben Compaine and Jack Shafer, find Bagdikian's critique overblown. Shafer noted that U.S. media consumers have a wide variety of news sources, including independent national and local sources. Compaine argues that, based on economic metrics such as the Herfindahl-Hirschman Index, the media industry is not very highly concentrated and did not become more concentrated during the 1990s and early 2000s. Compaine also points out that most media mergers are not purely acquisitions, but also include divestitures.
The "Big five"
American public distrust in the media
A 2019 Gallup poll found that Americans remain largely mistrustful of the mass media. Between 2017 and 2019, 41%-45% of respondents have had "a great deal" or "fair amount" of trust in newspapers, television and radio to report the news "fully, accurately and fairly." Distrust had increased since the mid 2010s when Americans were already more negative about the media than they had been before 2004.
In the UK, during 1922, after the closure of many radio stations, the British Broadcasting Company started its first daily radio transmission and started to grow an audience. Later that year John Reith, a Scottish engineer, would be appointed the first General Manager for the BBC. Later on January 1, 1927 the BBC was fully established by Royal Charter and renamed the British Broadcasting Corporation with Reith as the first Director-General. During November of 1936 the BBC began to expand into television broadcasting and was the first broadcaster to start the trend of a regularly scheduled TV service. 
Today the BBC is one of two chartered public broadcasting companies in the United Kingdom. The second is ITV, Independent Television, which was established in 1955 as the first public commercial television company after the Television act of 1954 in an effort to break up the monopoly the BBC had on television broadcasting, gaining fifteen regional broadcasting licenses in less than twenty years.  Today the BBC and ITV are the two free to air digital services offered to everyone in the United Kingdom and each others biggest competitors. The BBC has nine national television channels, BBC three, the first channel to switch from television to online, an interactive channel, ten national and forty local radio stations, BBC Online, and BBC Worldwide. ITV currently holds thirteen of the fifteen regional broadcasting licenses in the United Kingdom that carries their multiple channels including ITV, ITVhub, ITV2, ITVBe, ITV 3, ITV4, CITV, ITV Encore, Britbox, a video-on-demand service in collaboration with the BBC to bring British television content to the United States and Canada, and Cirkus, their own video-on-demand service. 
|Wikiquote has quotations related to: Mainstream media|
- Agenda-setting theory
- Alternative media
- Big Three television networks
- Concentration of media ownership
- Corporate media
- Fake news
- Freedom of speech
- Freedom of the press
- Lists of corporate assets
- Local News Service
- Media bias
- Media conglomerate
- Media cross-ownership in the United States
- Media democracy
- Media imperialism
- Media manipulation
- Media proprietor
- Media transparency
- Monopolies of knowledge
- Network neutrality
- Old media
- Partido da Imprensa Golpista
- Politico-media complex
- Prometheus Radio Project
- Propaganda model
- State controlled media
- Telecommunications Act of 1996
- Western media
- Chomsky, Noam, "What makes mainstream media mainstream", October 1997, Z Magazine, 
- 2013, Olesya Tkacheva, Internet Freedom and Political Space, p. 35
- CBS News (cbsnews.com), "Sarah Palin: Obama's Policies Are 'Un-American'", April 14, 2010, 
- Politico (politico.com), "Sarah Palin trashes 'lamestream media'", 11/18/09, 
- Los Angeles Times, "'Tea party' protesters in Nevada target health law, Reid", March 28, 2010
- Steiner, Tobias. "Under the Macroscope: Convergence in the US Television Market between 2000 and 2014". academia.edu. Retrieved 4 Aug 2015.
- Entertainment More: Infographic Media Corporation Mergers And Acquisitions These 6 Corporations Control 90% Of The Media In America, Business Insider (June 14, 2012).
- Shafer, Jack (2004-08-04). "The media monotony". Slate Magazine. Retrieved 2020-04-08.
- Ownership Chart: The Big Six. (2009) Free Press. Retrieved from http://www.freepress.net/ownership/chart/main Archived 2012-02-07 at the Wayback Machine
- "Comcast 2018 Revenue". CMCSA.com. CMCSA.com. Retrieved 15 July 2019.
- "Disney 2018 Revenue" (PDF). TheWaltDisneyCompany.com. TheWaltDisneyCompany.com. Retrieved 15 July 2019.
- "News Corp officially splits in two". BBC News. Retrieved June 29, 2013.
- "News Corp 2018 Revenue". NewsCorp.com. NewsCorp.com. Retrieved 15 July 2019.
- "21st Century Fox 2018 Revenue". 21cf.com. 21cf.com. Retrieved 15 July 2019.
- "WarnerMedia 2018 Revenue" (PDF). ATT.com. ATT.com. Retrieved 15 July 2019.
- Inc, Gallup (2019-09-26). "Americans' Trust in Mass Media Edges Down to 41%". Gallup.com. Retrieved 2020-01-25.
- "U.S. Distrust in Media Hits New High". Gallup. September 21, 2012.
- "History of the BBC-1920s". BBC.com. Retrieved 18 November 2018.
- "History of the BBC-1930s". BBC.com. Retrieved 18 November 2018.
- "About ITV/History". Itvplc.com. Retrieved 19 November 2018.
- "Television Act of 1954". The National Archives. Retrieved 19 November 2018.
- "BBC at a glance". BBC.com. Retrieved 18 November 2018.
- "About ITV/ What we do". itvplc.com. Retrieved 19 November 2018.