Mainstream media (MSM) are those media disseminated via the largest distribution channels, which therefore represent what the majority of media consumers are likely to encounter. The term also denotes those media generally reflective of the prevailing currents of thought, influence, or activity.
Large news conglomerates, including newspapers and broadcast media, which underwent successive mergers in the U.S. and elsewhere at an increasing rate beginning in the 1990s, are often referenced by the term. This 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, often in oppositional, pejorative, or dismissive senses, in discussion of the mass media and media bias.
Accordint to philosopher Noam Chomsky, media organizations such as CBS and The New York Times set the tone for other smaller news organizations by creating conversations that cascade down to smaller news organizations lacking the resources to do individual research and coverage, the primary method of which is through the Associated Press, from which many member or subscribing organizations get their news. This results in a recycling effect ,wherein organic thought is left to the mainstream that choose the conversation and smaller organizations recite absent of a variance in perspective.[clarification needed] The advent of the internet has allowed for a more diverse or alternative viewpoint which may contrast to mainstream media.
Lamestream media, a pun based on replacing the word "main" with "lame" in the word "mainstream," is a pejorative alternative term. Sarah Palin has referred to "lamestream media," notably during her participation in the Tea Party Express, in the context of what she perceives as media misrepresentation of the Tea Party movement.
- Chomsky, Noam, "What makes mainstream media mainstream", October 1997, Z Magazine, 
- 2013, Olesya Tkacheva, Internet Freedom and Political Space – Page 35
- dailykos.com, "MSM" vs "Traditional Media", August 8, 2007
- 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,