Not that that is a bad place to begin, but the answer that is usually given can be as confusing as the question itself.
Art is the practice of creating perceptible forms expressive of human feelings.
Langer goes on to explain that she is talking about the feelings which we all share as a culture, not just those of one person. Therefore, it might be a good idea to take a look at the term culture. After all, art is a large part of culture. Culture Culture has several meanings, such as that stuff that grows in the bottom of a petrie dish in biology class. But, another sense of the word culture is the one we use when we talk about those ideas and ways of doing things that are shared by those groups of people.