(Edit: A friend of mine wasn't familiar with the Team Jacob/Team Edward meme, so I summed it up in a few short sentences (contains mild Twilight spoilers):
Edward is a vampire. Bella fell in love with him. He didn't think things would work out. He dumped her. Bella was sad.
Jacob is a werewolf. He fell in love with Bella and hated Edward for hurting her. She just wanted to be friends. Jacob was sad
Edward came back and things got all mixed up. Some people thought Edward was a jerk, some thought he was just trying to protect Bella.
Jacob overstepped his bounds, and some people thought he was a jerk, some thought he was just a dumb boy.
Bella fell in love with both of them (I haven't read the last book yet).
Hence you are either Team Edward or Team Jacob (I was Team Bella, but that's not an option).)