The Streisand effect is an unintended consequence of attempts to hide, remove, or censor information, where the effort instead increases public awareness of the information.

The term was coined by Mike Masnick after Barbra Streisand attempted in 2003 to suppress the publication of a photograph showing her clifftop residence in Malibu, taken to document coastal erosion in California, inadvertently drawing far greater attention to the previously obscure photograph. The effect exemplifies psychological reactance, in which the attempt to hide information instead makes it more interesting to seek out and propagate.