What causes finger warts, and what are different types of warts?

I have been plagued long enough by these bastard warts on my fingers! I've had all of them frozen, with two successfully having come off, but the others stick around to mock me. I have one particularly gross one on my ring finger which is embarrassing considering I'm engaged and wouldn't like to wear a ring on that finger...so I was wondering what are the different types of warts, and where the hell do they come from? I've noticed all of mine have those dark spots in them, or the "seeds"...I've just applied nail polish to the bastards to try and cut off the air supply, but I would like to know more about warts and what I'm up against.