WoW World of Warcraft Priest
The Priest is the number one healing class, a must for a good group. The Priest can also manage hate and crowds, resurrect dead players and buff other players. The Priest is most useful in groups but can also solo when needed, thanks to the Shadow Magic spells. Detailed Priest guides can be found at Skryer.
One of the most useful spells that a Priest has is the Holy Word: Shield spell. It instantly shields a target and absorbs X damage. The shield works best on weak players like casters but also on tanks. The Priest has a few different buffs; one of them is Holy Word: Fortitude which increases the Stamina of the buffed player.
Along with all the healing spells and protection spells the Priest also has damage spells like Holy Smite, Mind Blast and Shadow Word: Pain. Other crippling spells are Mana Burn and Mind Rot (Drains mana).
As mentioned, the Priest has a few Crowd/Hate Control abilities too that reduces Hate and helps the Priest stay alive much longer.