We play on yahoo answers at work.... and its ooo so fun!
Actually one of the best quick and easy answers I have heard is "we create visual solutions to communication problems" and create ways to get a message across for our clients. Thats the short version.
Experience required, degree never hurts, not always required many places go off portfolio and experience alone, but cant go wrong with education. Then just pay your dues like the rest, prove yourself and abilities.
Again this is the short cliff note version..
Good luck on the report!