The Paladin class is available to Humans and Dwarves, in the Expansion The Burning Crusade this will expande to include the Blood Elves and Draenei. A Paladin is a Holy Warrior that draws his power from the "Light". The class is a hybrid of a Warrior and a Priest. As a result the class has the highest survivability of any class in the game while sacrificing burst damage output. This places the Paladin in a more support role upon reaching the end-game content.
Pros: Can heal themselves and others. Have benifitial blessing that aid friendly targets. Auras that add secondary benefits to party members within proximity to the Paladin. Resurrect fallen friendly targets. Wear the highest armor class in game (Plate) after level 40. At level 40 receive a free mount through a simple quest. Extremely high survivability.
Cons: Low DPS. No standard ranged abilities. May have difficuly being the Main Healer or Main Tank due to being hybrid.
The Paladin has the only 60 minute cooldown abilities in the game; Lay on Hand, this ability will heal the target for for an amount equal to that of the Paladins entire health, at increasing ranks of this ability there is a nominal mana gain also. With points spent in talent this abilities effectiveness can be increased and the cooldown decreased. Divine Intervintion: The Paladin Sacrifices themself to save a friendly target. This creates a bubble around the target that makes them loose all aggro, immune to attacks for 3 minutes but during this time may not act.
Other unique abilities: Blessing of protection, will make the friendly target immune to all physical damage for 4 seconds this increase to 8 at the higher ranks of the spell.
Divine Protection The Paladin is immune to all physical and magic effects for 6 this scales up to 8 seconds at the higher ranks. During this time the Paladin my not attack. Divine Protection The Paladin is immune to all physical and magic effects for 10 this scales up to 12 seconds at the higher ranks. During this time the Paladin my attack at half speed. This ability becomes available after Divine Protection.
Paladins are the tank/healer hybrid class. At higher levels the Paladin excels at absorbing damage. Paladins have Auras(spells that affect your entire group. Only one aura per paladin can be applied to the group.) Blessings (buffs which usually last 10 minutes and can be cast on the paladin and others), and seals (30 second offensive spells) or the ability to use judgements in conjunction with seals, which modify the effects of judgements.
Paladins also have limited abilities as healers but are usually only adequate as back up healers.
Paladins are also one of only two classes that get a summoned mount that is free at level 30 (was 40 until recent patch)