A form of armour that involves interwoven rings (ringmail is slightly different) of metal, normally worn as a suit for protection in combat. It was lighter than plate armour and offered better protection than leather and was, therefore, a popular choice for light troops (or early armies, who didn't have the option of plate). It was slowly (but not entirely) phased out on line troops as plate armour became less expensive and lighter (though it was often used to cover the joints of the armour and was sometimes worn under the armour for added protection).
At the battle of Crecy, the non-noble troops on both sides wore mostly chainmail. However, this made the French soldiers fatally vunerable to English longbow fire.