In this article, Feminist Germaine Greer tells us what art is. Interesting read.
One example: "Our best artists make stuff they know is bad; the difference is that they destroy it themselves. Tracey Emin didn't wait to be told to destroy the paintings that earned her an MA at the Royal College of Art. There are a few dealers around the place who would kill to get their hands on them; she has made sure they never will. That's the kind of thing real artists can be expected to do."