The hood was originally a functional garment, worn to shield the head from the elements. In the English tradition, it has developed to an often bright and decorative garment worn only on special occasions. Hoods comprise two basic patterns: full shape or simple shape. The traditional full-shape hood consists of a cape, cowl, and liripipe, as is used at Cambridge. At Oxford, the bachelors' and masters' hoods use simple hoods that have lost their cape and retain only the cowl and liripipe. The colour and lining of hoods in academic dress represents the rank and/or faculty of the wearer. In many Commonwealth universities bachelors wear hoods edged or lined with white rabbit fur, while masters wear hoods lined with coloured silk (originally ermine or other expensive fur). Doctors' hoods are normally made of scarlet cloth and lined with coloured silk. Faculty colours were introduced by the University of London and many universities followed suit.