A surcoat is a loose-fitting garment worn over armor, primarily during the Middle Ages. It was often made of fabric and featured a design or emblem that represented a knight's heraldry. This allowed knights to be easily identified on the battlefield, as the surcoat displayed their family crest or colors. Surcoats were not only practical but also served a decorative purpose. They could be made from various materials, including silk and wool, and were sometimes lined for added warmth. The use of surcoats became popular in the 12th century and continued until the late medieval period, evolving in style and function over time.