Founded by the Romanian-born artist Isidore Isou in the mid 1940s, this French avant-garde movement was associated with the Situationist branch of the Anarchist family and became the art that dominated posters and barricades in the Paris Spring of 1968. Lettrisme is a form of visual poetry: using calligraphic techniques it began by artists superimposing letters on various objects from furniture to film. This practice foreshadowed layering and other computer techniques, and because of this it is sometimes called hypergraphie. Both Mail art and contemporary Graffiti art, which share many of the Lettrisme's basic characteristics, could be said to have evolved out of Lettrisme.