An art movement, or ism, is a style in art. It may have a common philosophy, followed by a group of artists. It may be a label given by a critic to describe a type of artwork. It is typical of the post-photography era that art explores new directions.
Some art movements can be pinned down to a time and place, or to particular artists. Verbal explanation of movements may come from the artists themselves, sometimes in the form of an art manifesto (published statement). Quite often, a movement is labelled afterwards by some art historian or critic.