An activated ability is a bonus or skill that requires a command from the player to begin. The opposite of an activated ability is a passive bonus, which occurs on its own. While most traditional abilities are activated abilities, so is the use of select items. Core of Ar'kelos, for instance, "Increases your melee and ranged attack power by 200. Effect lasts for 20 seconds." This effect only occurs if you "use" the item, by right-clicking it or by using it from an action bar.