While we call it chain mail today, often in Medieval times it was just referred to as mail. It was worn by knights from around the 9th century until around the 13th century as the main type of armour, although some knights continued to wear the chain mail under plate armour up until the 15th century.
Chain mail was made from hundreds of small iron rings that interlocked. They were also held together with the help of rivets. The aim of the design was for the chain mail to lie on the body’s own contours. There was a huge range of garments that could be made from chain mail including trousers, hooded coat, gloves, and even shoes. The only part of the body that would not be covered was the face. Coats – or hauberks – were often knee-length. Leather laces helped to draw the garments tighter in various places so to avoid exposing the skin. The actual hood would be lined or have some sort of padding on the inside so that it would be more comfortable for the wearer.
The chain mail trousers would often be worn over leggings to make it more comfortable to wear. Sometimes they added discs to protect the knees a little more. On top of all of this, a surcoat of cloth would be worn. The wealthier knights would have these made from silk. This would also be knee-length and would be tied with a belt. It may often feature the coat of arms of the knight if they wanted to display a symbol of their wealth and power, but many chose to wear a plain surcoat. Some consider that the surcoats may have given added protection from the elements.
However, all of this was very heavy to wear, and knights needed to learn to move around in it. In addition, it did not offer protection from all types of weapons.