Unbreaking

Unbreaking is an enchantment that increases the effective durability of an item.

For most items,  chance a use reduces durability. On average, lifetime is (Level+1) times as long.

For armor,  chance a use reduces durability (each durability hit against "unbreaking" armor has a 20%/27%/30% chance of being ignored). On average, armor lasts 25%/36%/43% longer.

When durability is reduced by multiple points (e.g. hooking a mob with fishing rods or Thorns armor), Unbreaking is applied for each point of reduction.