What different backstabbing techniques are there?

I'm sure most people know about backstabs, where you run up to people's backs, and you....well, stab them. In the back.

But I've heard about other stabs as well, and since I'm trying to be a lot better as a spy, I've heard about different kinds of stabs, like sidestabs, facestabs, trickstabs, and jukestabs.

What kind of "stabbing" techniques are there, and how do I perform them?