Along with satin and plain weave, twill is one of the three original types of weaves used for textiles. Rather than denoting a certain type of fabric fiber, "twill" refers to a specific type of weaving that results in a diagonal pattern. For contrast, both satin and plain weave have straight patterns.
Fabrics have been woven in twill patterns for thousands of years, which makes it hard to determine where exactly this type of fabric originated. However, the word "twill" is a modern variant of the Old English word "twili," which is a half adoption of the Latin word "bilix." Therefore, twill is commonly associated with British culture even though this type of fabric has been woven in other cultures for much longer.