Surrealism

Surrealism is a movement in which artists and writers express the ideas formed in their subconscious imagination. Not only did this movement influence art, it also influenced fashion photography, advertising and film. To create a surreal piece, artists combine a selection of objects (usually two) hat you wouldn't associate with each other to make something playful, or even disturbing.

The movement began in 1924 in Paris, by French poet Andre Breton. Well known surrealist artists include Salvador Dali, Rene Magritte and Man Ray.

Rene Magritte - The Son of Man, 1946

Max Ernst - Celebes, 1921

Rene Magritte - The wonders of nature, 1953

Sources:
http://www.tate.org.uk/learn/online-resources/glossary/s/surrealism