Trained as a painter, Marcel Duchamp made a radical break with traditional art by inventing the "readymade." A readymade is a pre-existing, industrially produced object — e.g. a bicycle wheel, urinal, or bottle rack — that the artist placed on a pedestal with little or no modification.

These banal items became art simply because Duchamp chose to declare them as such and to display them in the rarified space of the museum or gallery. In so doing, he called into question art's emphasis on craft and the unique aura bestowed by the artist's hand.

Duchamp brought European avant-garde ideas to America when he immigrated in 1915. He later abandoned art for chess, but his methods (which also include wry, self-referential assemblages) paved the way for much of the art of the second half of the century.