Historically, graffiti was an underground movement, born to the Hip-Hop rhythm in the American ‘hoods of the 1970s. It is people’s art, rough and ephemeral. Rough because it was created illegally in public spaces. Ephemeral because its lifespan, subject to external constraints, is necessarily limited. The prohibitions which hit this urban art right from its beginnings in Europe could not stop its expansion during the 1980s. At the end of the decade it had become a veritable fashion phenomenon, in the press and on museum walls. Aside from urban buildings, street furniture and public transport, the graffiti artists created works on canvas, paper or street hoardings which are now prized by a growing number of collectors.