So far Ben Davis has provided me the best definition of art I have ever heard:
http://www.artnet.com/magazineus/reviews/davis/art-and-social-media8-4-10.asp
I would add that art cannot be mass produced or it becomes another object that was designed.
Important to note:
Fashion, design, craft, music, architecture, food, theater are all incorporating or moving into art.
Also: the difference between good art and bad art is much more complex.