Caps and gowns have their origins in medieval Europe. Students attending universities were subject to church law and therefore were expected to conform to the same dress code as members of the clergy: a long cloak or tunic and a hood. Oxford and Cambridge are credited as the first European universities to mandate specific requirements for regalia at university functions. Universities in the United States standardized the color code for students in the late 19th century.
Tams, short for Tam O'Shanters, are worn by recipients of doctoral degrees at some institutions. The most common cap worn in academic dress is the mortar board, also known as the Oxford cap. The name "mortar board" comes from its similarity in appearance to the mason's tool of the same name. The mortar board is always black and made of a material matching the gown. Tassels are attached to the middle of the cap and generally correspond to the subject of study.
Gowns are made from a variety of materials but are almost always black. They differ in cut and the manner worn depending on the degree conferred. Gowns for bachelor's degrees are untrimmed and have pointed sleeves. Gowns worn by master's students are also untrimmed, but the sleeves are square-cut in the rear and have an arc cut away in the front. Doctoral robes are faced with black velvet in the front and with colored velvet along the sleeves. The color of these velvet bars indicates the discipline in which the person has trained.
Hoods are always made of the same material as the gown but vary in length depending on the degree conferred. The hood worn for a bachelor's degree is the shortest and that worn for a doctoral degree is the longest, with a master's hood being of intermediate length. The lining of a hood is the official color of the school conferring the degree. Trimming on the hood indicates the student's area of study.
The American Council on Education standardized the colors that signify specific areas of study for academic regalia in the United States: humanities, white; education, light blue; journalism, crimson; medicine, green; science, golden yellow. A degree recipients for one of these degrees should have the appropriate-colored tassel and trim on their hood. If a Ph.D. has been earned, velvet bars on the sleeve of the gown will also be of the appropriate color.