A paladin is a knight of a holy order, in service to a god. Where a cleric serves his god through worship and prayer and deeds of faith, a paladin serves his god through his honour, combat, and deeds of chivalry.
Paladin are not permitted to join other classes, like mage, or thief. And while they have both fighter and clerical skills and spells they only have to pay x1 the exp cost, rather than the x2 exp cost.
Paladin gain 12 hit points per advancement of constitution. When a player becomes a paladin, his original hit points are recalculated to this new hp multiplier.
Please view "man paladin" and "help paladin" on the mud for additional information.