Surrealism was born in France around the 20's and its founder was André Breton.
This avant-garde was influenced by another artistic movement called "Dadaism", taking some techniques related to photography and cinema. Also, the surrealism used new ways to express their feelings and ideas with automatic writings without a logical sense.
The artist who take part of the surrealism work with figures as the collage (as the cubism) and "Cadáver Exquisito", sticking all their differents works and creating one new completely confused.
They had a new vision of the things and their way to representate it was support in topics like the dreams and methafors for the paint and for the literature, they try to found new techniques of composition. In both, the idea was search one truth trough this methods doesn't very rationals.
We usually related to this movement artists like Salvador Dalí and René Magritte, but also Man Ray, Alberto Giacometti, Miró, Masson, etc, who participated in the exposititions.
In cinema, Luis Buñuel and Hitchcock, two recognized directors, work with the surrealism too in movies like "Perro andaluz"and "Spellbound", respectively.
I don't choose this avant-garde only because I considered interesting how they work and how you could read and interpret the final work, but I don't think that this one it's most important than the others, because each one has something different and innovative.