A flash mob is a group of people who meet in a public place at a specific time to perform a random and seemingly pointless act, then disperse without explanation. Flash mobs generally perform these acts for the purposes of entertainment or artistic expression, though some flash mobs have resorted to crime. These groups are usually organized through social media, mass emails and websites.
The term flash mob is not used to describe groups that suddenly organize for the purpose of protest or other political activism. In these cases of a planned purpose for the social activity in question, the term smart mobs is often applied instead.
The first flash mob formed in Manhattan in 2003 at a Macy's department store, as more than 130 people converged in the rug department. The event was organized by an editor at Harper's Magazine.