Mainstream media (MSM) is mass media reflective of prevailing currents of thought, influence, or activity. It may be contrasted with alternative media which may contain content discordant with prevailing views.
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.
According to philosopher Noam Chomsky, media organizations with an elite audience such as CBS News and The New York Times, successful corporations with the assets necessary to engage in original reporting, set the tone for other smaller news organizations which lack resources by creating conversations that cascade down to smaller news organizations using the Associated Press and other means of aggregation. An elite mainstream sets the agenda and smaller organizations parrot it.
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
- 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,