Caricature is broadly defined as a portrait of a person that is exaggerated for comic effect. But for real world purposes, we should say that a caricatures is a cartoon of a person that looks enough like an individual so that you can still recognize him/her.

Like my Commander Guy...

From Cartoon People

Sure, it's goofy, but if you aren't blind you should be able to tell that it is George Bush!

I'm a landscape painter who has done some pencil and painting portrait work in the past. Now I'm trying to learn caricature art in the hopes of making a buck - FINALLY - off of art.

I'm not really that optimistic about it, but there you go...