Damage

Damage is a measurement of how harmful an attack is to a character. When a character takes Damage, it is subtracted from their Hit Points. Damage will cause death when a character's hit points reach 0.

Influences
Weapons all have base damage values. The final damage delivered to the target, can be possibly modified by various factors, depending on the game:

Fallout: New Vegas features a few weapons that completely ignore DR, even if few enemies actually have DR.

Damage done to the player in V.A.T.S. is reduced by 90%.

Damage done to the player in V.A.T.S. is reduced by 25%. Melee/unarmed damage done by the player is doubled.

Types
There are different types of damage, depending on the weapon of attack:

Not shown in the games that use it, Electrical damage is only caused by alien blaster, YK32 pulse pistol, and YK42B pulse rifle.

Fallout 3 and Fallout: New Vegas use "energy" damage to label the residual effect off the Tesla cannon, though it has the appearance of electricity sparking.

All Fallout games contain environmental radiation damage of some variant. The table is representative of radioactive damage dealt by weapons like the gamma gun.

Exists in the game files, but is not used anywhere.

Special exceptions

 * Fallout Tactics adds Gas Damage. It also re-categorizes "Laser" as "Energy" damage.
 * Van Buren adds Ballistic, Bio, and Heat damage.