A guige is a long strap, typically made of leather, used to hang a shield on the shoulder or neck. This technique was primarily done when the shield was not in use. Nevertheless, soldiers also wore the strap in this fashion in combat: it allowed the two-arm combat: to handle a second weapon, to allow the shield be worn on the back while using a two-handed sword, to use a spear with two hands or various siege machines without discarding the shield, etc.
Some guiges had buckles to adjust its length. They could be attached to the shield in different ways: in the upper part, upside down, diagonally, or diametrally.
Most information about the usage of guiges comes from various Mediaeval works of art, such as the Bayeux Tapestry.