A demonstration or street protest is action by a mass group or collection of groups of people in favor of a political or other cause; it normally consists of walking in a mass march formation and either beginning with or meeting at a designated endpoint, or rally, to hear speakers.

Historian Eric Hobsbawm says, "Next to sex, the activity combining bodily experience and intense emotion to the highest degree is the participation in a mass demonstration at a time of great public exaltation. Unlike sex, which is essentially individual, it is by its nature collective...and it can be prolonged for hours....It implies some physical action--marching, chanting slogans, singing — through which the merger of the individual in the mass, which is the essence of the collective experience, finds expression."