Protection

Protection is an enchantment applied to armor that increases the armor's damage reduction.

Usage
Protection has no effect on damage from the void, the command, or hunger. $$, protection does not reduce damage from negative status effects like poison or wither. Otherwise, the damage is reduced, even if armor normally would not protect against it (e.g. damage from using ender pearls). When enchanted armor reduces damage from a source that armor does not normally protect against, it does not lose any durability.

The formula for damage reduction is for each armor piece. However, $$ armor pieces with Protection IV use, or in other words Protection IV functions as if it were Protection V.

Damage reduction from Protection, Fire Protection, Feather Falling, Blast Protection, and Projectile Protection stacks up to an upper limit of 80% (see armor enchantments). $$ a full set of armor with Protection IV is sufficient for this maximum amount of protection.

The protection enchantment is applied after the armor's damage reduction. For example, 20 armor points provide a 4% * 20 = 80% damage reduction. If the total protection enchantment levels on said armor adds up to 10, they would provide 40% damage reduction. This would equate to a result of 88% damage reduction, as it stacks multiplicatively rather than additively (80% + 40% * (100% - 80%), rather than 80% + 40%).

Incompatibilities
Protection, Blast Protection, Fire Protection, and Projectile Protection are mutually exclusive. However, if commands are used to have two or more of these enchantments on the same item, the effects stack.

ID