Collage [French "coller" = to gum, to stick] is produced by pasting materials on to flat surfaces, often in layers, to create a new aesthetic whole. All sorts of materials may be used, such as newspaper cuttings, colored paper, tape, pieces of veneer, photographs and the like, which are pasted to a firm ground or canvas. The collage technique was used by the Futurists. It was particularly appreciated by the Dadaists and Surrealists for the surprising effects and absurd combinations that can be created with it and because it allows scope for the free play of chance. Max Ernst defined collage as follows: "The collage technique is the systematic exploitation of the coincidental or artificially provoked concurrence of two or more essentially dissimilar realities on a plane that is evidently unsuited - and the poetic spark which leaps across when these realities approach one another." Collage as an artistic technique was used before then; Georges Braque and Pablo Picasso introduced it in modern art around 1910/11. When the collage technique is used for three-dimensional objects, it is called assemblage.