What is the difference between data mining, statistics, machine learning and AI?

There is considerable overlap among these, but some distinctions can be made. Of necessity, I will have to over-simplify some things or give short-shrift to others, but I will do my best to give some sense of these areas. Firstly, Artificial Intelligence is fairly distinct from the rest. AI is the study of how to create intelligent agents. In practice, it is how to program a computer to behave and perform a task as an intelligent agent (say, a person) would.