Paladins are all about buff combos. Each Paladin has three standard buff types, auras, seals, and blessings. Auras are always active red war gold, but you can only activate one at a time.
Auras affect all members of the Paladin's party. Blessings are short buffs that can be cast on any party member. Seals are very short self-buffs that are used to enhance the Paladin.
The Paladin deals holy damage to all surrounding enemies while enemies he uses the crusader seal to cause extra holy damage to his target.
Group ability 6: Paladins can have two functions in a group, tank or secondary healer. As a tank, the Paladin's job is simply to absorb damage and hold agro. As a secondary healer, the Paladin can keep an ally healed to some extent in the fray of battle.
Though not as good as healing as the Druid, Paladins have enough mana to keep an ally healed for a decent duration. The negative side to Paladins in groups in that ally constantly wants seals; this can drain your mana and be quite repetitious.