It goes without saying that in the world of warcraft, Mage is well-known glass cannon. In the game, they have some of the highest damage output and many necessary abilities that high level raiding absolutely needs. If anything needs to be AoE'd down then a Mage is the one you'd want to call. To balance this out they have little defense like the rest of the casters. They're restricted to cloth armor only and rely on their magic to beef up their defense and help them gain distance. Not only that, but their damage is restricted to a resource known as mana which means they need mana in order to do damage, defend themselves, and provide the much needed utility that groups need. In a word, the Mage is a very fun and exciting class with a lot of flexibility that really shines to someone who likes to fight from a distance.
   Mostly, the ranged DPS and utility class focus on ranged single target and area of effect spells with fire, ice, or arcane magic. They offer high levels of utility (especially at later levels) with their various utility spells like Polymorph which can turn an enemy into a critter removing them from battle. They can summon food and water, steal the spells of their enemies, lock their enemies' magical abilities down, and have the option of summoning a temporary pet to aid them in battle. There is a lot more than just hurling fiery death at enemies to explore for the Mage.
   Both in PVE and PVP, the Mage is highly in demand. On the hand, the Mage supplies many highly needed crowd control abilities that no other class has access too along with a very high amount of damage in PVE. Even solo they're a powerful force being able to often slay their enemies before even reaching the Mage's fringe on their robes. On the other hand, the Mage offers the greatest asset of all which is crowd control in PVP. Many Arena games are decided by how fast Mages can get their Polymorph spells off and in the battlegrounds, you won't find a better source of AoE damage than the Mage. They do have issues with defense, but with abilities like Frost Nova, Cone of Cold, Ice Block, and Blink they're able to escape many situations unscathed.
   In order to wreck havoc on enemies and aid allies, the Mage utilizes a large toolbox of options. The abilities are split up into three categories like direct damage, area of effect, and utility. Direct damage is comprised mainly of burst damage spells like Fireball, Frostbolt, and Arcane Missiles. Area of Affect includes Arcane Explosion, Blizzard, and Frost Nova. Finally, utility includes Polymorph, Spellsteal, Counterspell, and Summon Food and Water.
As the most prominent direct damage abilities, Fireball and Frostbolt are the primary source of damage and provide additional affects such as a DoT with Fireball and a snare with Frostbolt. At higher levels they can get Frostfire Bolt which allows them to mix the elements into one attack.
We often hear Blizzard say that their specialty is within the area of effect damage spells and Mages are loaded with them. You have Arcane Explosion which is an instant PBAoE ability (damages around the caster), Frost Nova which roots all enemies around the Mage, Blizzard which is a ground targeted channeled AoE ability, and Flamestrike which is like Frost Nova but does massive damage and only snares.
For utility spells, Polymorph ability can transform any enemy into a cuddly critter effectively taking them out of battle. It is important for both PvE and PvP by decreasing the effective amount of active combatants in battle putting the numbers in favor for your side. But Spellsteal ability will allow you to steal an enemy's spell for a short duration and Counterspell which can silence the enemy. Conjure Food and Water can summon refreshments for the Mage and its allies.