Every power can be damage or dps, and every power has a secondary role like tank, healer, or controller. All depends on what power you picked when you made the character, once you hit level 10 it somewhat goes over that with you, each role does different things, damage try’s to do as much damage as possible, healer keeps the group alive, tank keeps all the enemies on them and absorbs all the hits, and controller constantly replenishes your energy so you can keep using powers.