Short answer: yes (although there are powers/paragon path of other classes that mark).
Long answer: marking gives a -2 to attacks from the affected creature that don't target the marking character; depending on what placed the mark, other effects may apply (e.g. Fighter's Combat Challenge and Paladin's Divine Challenge).
Specifically, a Paladin can mark foes with his Divine Challenge and several of his powers. Most of the Fighter's marking happens through Combat Challenge, which means that whenever he attacks a foe, and whether he hits or misses, the target is marked until the end of the fighter's next turn.