The concept of citizen journalism (also known as "public", "participatory", "democratic","guerrilla" or "street" journalism) is based upon public citizens "playing an active role in the process of collecting, reporting, analyzing, and disseminating news and information." Similarly, Courtney C. Radsch defines citizen journalism "as an alternative and activist form of newsgathering and reporting that functions outside mainstream media institutions, often as a response to shortcomings in the professional journalistic field, that uses similar journalistic practices but is driven by different objectives and ideals and relies on alternative sources of legitimacy than traditional or mainstream journalism."Jay Rosen proposes a simpler definition: "When the people formerly known as the audience employ the press tools they have in their possession to inform one another."

Citizen journalism should not be confused with community journalism or civic journalism, both of which are practiced by professional journalists. Collaborative journalism is also a separate concept and is the practice of professional and non-professional journalists working together.

Similarly, Social Journalism is a separate concept denoting a digital publication with a hybrid of professional and non-professional journalism. Citizen journalism is a specific form of both citizen media and user generated content. By juxtaposing the term “citizen,” with its attendant qualities of civic mindedness and social responsibility, with that of “journalism,” which refers to a particular profession, Courtney C. Radsch argues that this term best describes this particular form of online and digital journalism conducted by amateurs, because it underscores the link between the practice of journalism and its relation to the political and public sphere.