In this introduction Cottington traces the history of the avant-garde and my understanding is that the avant-garde refers to innovative, experimental, creative work that provides an alternative to the art of the establishment, or academic. It is involved in a cycle in which an avant-garde is created, which challenges established art, notions, and tastes, but then becomes popular, and professionalizes, and slowly morphs into the new establishment. Eventually, a new avant-garde is needed to provide an alternative for the old avant-garde which has become the establishment.
The first avant-garde was created by Napoleon III as a way of taking power away from academies. He created art salons and invited only people who were rejected from major art prizes; thus, creating a new establishment out of those who were not accepted by the establishment.
This short introduction, was not as exciting as some others I've read, but it did its job of teaching me about the avant-garde. In the conclusion Cottington points to some possible futures, or describes the present, of the avant-garde, referring mostly to the development of non-western avant-garde.