Injury and Death (DMG)

Sometimes, no degree of luck, skill, ability, or resistance to various attacks can prevent harm from coming to a character. The adventuring life carries with it unavoidable risks. Sooner or later a character is going to be hurt.
To allow characters to be heroic, and for ease of play, damage is handled abstractly in the AD&D game. All characters and monsters have a number of hit points. The more hit points a creature has, the harder it is to defeat.
Damage is subtracted from a character's or creature's hit points. Should one of the player characters hit an ogre in the side of the head for 8 points of damage, those 8 points are subtracted from the ogre's total hit points. The damage isn't applied to the head or divided among different areas of the body.
Hit point loss is cumulative until a character dies or has a chance to heal his wounds.
Cwell the Fine, with 16 hit points, is injured by an orc that causes 3 hit points of damage. Fifteen minutes later, Cwell runs into a bugbear that inflicts 7 points of damage, Cwell has suffered 10 points of damage. This 10 points of damage remains until Cwell heals, either naturally or through magical means.
==Wounds==
When a character hits a monster, or vice versa, damage is suffered by the victim. The amount of damage depends on the weapon or method of attack. In Table 44 of the Player's Handbook, all weapons are rated for the amount of damage they inflict to Small, Medium, and Large targets. This is given as a die range (1d8, 2d6, etc.)
Each time a hit is scored, the appropriate dice are rolled and the result—damage—is subtracted from the current hit points of the target. An orc that attacks with a sword, for example, causes damage according to the information given for the type of sword it uses. A troll that bites once and rends with one of its clawed hands causes 2d6 points of damage with its bite and 1d4 + 4 points with its claw. The DM gets this information from the Monstrous Manual.
Sometimes damage is listed as a die range along with a bonus of +1 or more. The troll's claw attack, above, is a good example. This bonus may be due to high Strength, magical weapons, or the sheer ferocity of the creature's attack. The bonus is added to whatever number comes up on the die roll, assuring that some minimum amount of damage is inflicted. Likewise, penalties also can be applied, but no successful attack can result in less than 1 point of damage.
Sometimes an attack has both a die roll and a damage multiplier. The number rolled on the dice is boosted by the multiplier to determine how much damage is inflicted. This occurs mainly in backstabbing attempts. In cases where damage is multiplied, only the base damage caused by the weapon is multiplied. Bonuses due to Strength or magic are not multiplied. Bonuses due to Strength or magic are not multiplied; they are added after the rolled damage is multiplied.