Postmodernism is really a term that has no absolute definition. It is definied when it is applied to the art that would appear during the postmodern era. Postmodernism, in terms of art, is a term used to describe art which is thought to be after or in contradiction to some aspect of modernism. Postmodernism is the umbrella for all the movements that came after it such as Instillation Art, Feminism, Queer Theory, Multiculturalism, Deconstructuralism and Poststructuralism. It's a sharp break from everything modern that came before it. It doesn't really have a starting or ending time like many other theories and movements do and though this may be "modern" times we are still in the postmodern era.