Chain armor is very rare. It can only be legitimately obtained by villagers or by killing zombies or skeletons that are wearing chain armor
An armor provides a player protection from common damage. It reduces the damage received, but will lose durability.
An armor includes helmets, chestplates, leggings, and boots, which can each be placed in designated armor slots of a player's inventory.
Players, Horses, Zombie (Pigmen) and (Wither) Skeletons can wear armor.