"What is open source?"

I was on the Novell campus a few weeks ago attending the Utah Open Source Conference. One of the days I went to the Novell cafeteria for lunch. While I was filling my plate with food, a young man next to me asked, "So do you work here?". I replied with "No, I'm here attending the open source conference." A few seconds later I was hit with a question that I was not prepared to answer.

"What is open source?" he asked. I was speechless.