Mass media denotes a section of the media specifically designed to reach a large audience. The term was coined in the 1920s with the advent of nationwide radio networks, mass-circulation newspapers and magazines. However, some forms of mass media such as books and manuscripts had already been in use for centuries.

Mass media includes Internet media (like blogs, message boards, podcasts, and video sharing) because individuals now have a means to exposure that is comparable in scale to that previously restricted to a select group of mass media producers. The communications audience has been viewed by some commentators as forming a mass society with special characteristics, notably atomization or lack of social connections, which render it especially susceptible to the influence of modern mass-media techniques such as advertising and propaganda.

The term public media is less used and is defined as "media whose mission is to serve or engage a public."

Marshall McLuhan, one of the biggest critics in media's history, brought up the idea that "the medium is the message."