In Diablo III, the Wizard uses Arcane Power as its primary resource.
The Wizard is a playable class built around elemental and arcane magic. Its abilities include spells associated with fire, cold, lightning, and arcane energy. Arcane Power is spent to cast many of the class’s more powerful skills, while some abilities help restore or manage it.
The class replaced the Sorceress terminology used for the principal spellcaster in Diablo II. Although both are magic-focused, Diablo III’s Wizard has its own skills, resource system, runes, and story presentation.
Arcane Power is not the resource used by every magic-oriented class. The Witch Doctor uses Mana, while the Monk uses Spirit and the Demon Hunter uses Hatred and Discipline. These separate systems help distinguish the classes during combat.