Administrators can ban players from the game. There are two types of bans: round bans and perm (permanent) bans. Round bans ban the player from playing for the rest of the round, perm bans ban the player from ever playing again.
If you get booted, it resets your character so you go back to the screen. These are usually reserved if you're just being a general jerk in OOC or breaking a naming rule. It could also to be fix a glitch, so don't think it's just reserved for punishment.
Round bans are usually the less-troubling rules that are broken, so to be round banned you'd probably have to do something such as killing another person's tamed animal or normal metagaming. These are usually to warn you to quit breaking rules!
Perm bans are usually reserved for major rule breaking, like mass griefing, lots of metagaming, and other repeated offenses. You can appeal to be unbanned on the official forums.