From Diablo Wiki
Damage is the lowering of Player or Monster health points that eventually leads to the death of monsters and players.
- Physical, Damage done with Melee Weapons, Bows, Crossbows, and Javelins. Defense Protects against physical damage, physical damage is used my a majority of monsters.
- Fire, Damage from fire spells, aura's, fire enchanted weapons. Fire resistance protects against fire attacks, higher fire resistance protects from fire damage. 0 = Full damage, While, 100 = No damage
- Cold, Damage from Cold spells, aura's, Cold enchanted weapons. Cold damage can slow monsters and players and can freeze monsters in place. Cold resistance protects against Cold attacks and can lower cold length, higher cold resistance protects from col damage. 0 = Full damage, While, 100 = No damage
- Lightning, Damage from Lightning spells, aura's, Lightning enchanted weapons. Lightning damage is almost never the same, it normally does random damage from '1' to a certain amount of damage, EX. 1-275. Lightning resistance protects against Lightning attacks, higher Lightning resistance protects from Lightning damage. 0 = Full damage, While, 100 = No damage
- Poison, Damage from Poison spells, aura's, Poisoned weapons. Poison resistance protects against Poison attacks. Poisen does full damage over a certain amount of time, normally does Damage/Sec. Higher Poison resistance protects from Poison damage. 0 = Full damage, While, 100 = No damage
- Magic, Damage that occurs from certain spells, their is no resistance for players, but some monsters are immune to Magic Damage.