What is Art?

What do you classify as art? Is art the same for everyone? Is there some standard that all "art" must meet to truely be considered art?
When asked this question today in class I honestly didn't really know how I classify things as art or not. I mean if you think about it, why is the Mona Lisa considered art? Is it because it is a painting? Is it because that is what you have been told in school? After thinking about it all day I decided that art is personal. You define what is art. Art is something that moves you or relates your feelings through a creative means. A great example used in class was when MJ threw the keys on a stool. Now would I consider that art?... No... but was it art?... Maybe to someone else it truely meant something to them and therefore it would be art to that specific person. A good quote brought up today in class was "the beauty is in the eyes of the beholder". So therefore I don't believe that there are standards that art must meet to be considered art. I believe that art is something created with intention and when presented moves you or "speaks" to you.