Background: Officially, Wizards are renegade spell casters who "use their bodies as vessels for arcane energy, forsaking the more careful path favored by other magic users." They don't care about the caution and safety that mages and sorcerers learn in the academies throughout Sanctuary. Instead, they use arcane power to disintegrate, burn, and freeze their foes while also having the ability to manipulate light and time to teleport, create illusions, and deflect oncoming attacks.
Some of the key features of a Wizard include area attacks, protective spells, elemental mastery, and endless energy. Area attacks are spells that can hit large groups of enemies at once and punish them for standing close together. In Diablo 3 many of the enemies come in packs, and the Wizard excels at taking these large packs out quickly. Protective spells are basically what the Wizard uses as defense. They can encase themselves in ice or diamonds to absorb damage, or they can create mirror images to confuse their enemies. Protective spells also allow Wizards to snare and slow down enemies if they happen to somehow get their hands on you.
The main feature that you'll be using when it comes to Wizard is their ability to master the elements. Having power over flames, lightning, ice, and wind Wizards can use these elements to target their foes' weaknesses and destroy them. Finally, with the Wizard's endless energy and ability to quickly regenerate their arcane power they can almost cast their weaker spells if they find themselves in a pinch.