@MrsWinslow - My dad had a ham radio operator license, too! It's neat, isn't it? I had a friend who moved to Japan who sent me a message through a ham radio operator there.
It's basically just certain frequencies set aside for ham radio. Some of them actually use FM, just like the radio in your car, but at different frequencies than that would use. As you pass each level test, you are allowed to use other frequencies (higher ones, if I remember right).
The idea behind licensing is that it keeps yokels from cluttering up the airways! Unskilled operators can cause interference.
I've actually been thinking of getting a license myself. It seems like it could be particularly helpful in a disaster of any kind.