Paladin

Basic Information from Blizzard regarding Paladins: Upholders of the Holy Light and defenders of the Alliance, the Paladins can be found in the northern forests of the Tirisfal Glades, fighting back the advance of the Forsaken, to the southern reaches of the Blasted Lands, ceaselessly upholding their vigil against demonic forces from beyond the Dark Portal. Wielding their mighty hammers and the strength of the Light, these holy warriors command forces in battle, continuously throwing themselves into the fray wherever the fighting is the thickest.

The Paladin is a mix of a melee fighter and a secondary spell caster. The Paladin is ideal for groups due to the Paladin's healing, Seals, and other abilities. Paladins can have one active aura per Paladin in the party on each party member and use specific Seals for specific players. Paladins are pretty hard to kill, thanks to their assortment of defensive abilities. The Paladin can also heal with Holy Light, unlike other combat classes. The Paladin is an Undead specific fighter as well, with several abilities designed to be used against the Undead.

Valid Races: Human, Dwarf, Draenei, Blood Elf

The TenTonHammer take on Paladins

The Paladin is essentially a cross between a healer and a tank. While not as strong or as durable as a Warrior, once you factor in their seals and healing spells they are in no way inferior. While gaining combat skills similar to the Warrior they also gain healing spells similar to the Priest.

Paladins can also cast seals, which are spells that affect a singe player positively, such as increased damage. They also may use auras to effect all players around them. Combined with their combat abilities, this makes them an effective class that is almost a must have in Alliance parties.

Links to information on other WoW sites

Blizzard WoW site - The official Blizzard WoW Paladin information page.
Paladin Articles - Article submissions from players about Paladins on "The Knights who say... Ni!" site.
Paladin Character guide - Starting levels and brief talent descriptions at the wowvault.ign.com site.
The Holy Light - An entire site devoted to the Paladin class.