Many scholars believe the mortarboard style cap graduates don was developed from the biretta, a similar-looking Italian hat worn by Roman Catholic clergy. In the 12th and 13th centuries, students and teachers typically wore clerical clothing because the church was highly influential at this time. Medieval universities helped inspire academic dress, including the familiar graduation cap.

Mortarboards are shaped like a square, perhaps to give them a scholarly appearance like a book or to represent the shape of a quad on the campus of England’s Oxford University, where many graduation dress customs are believed to have originated. Others theorize that the mortarboard, which is named after the flat board used by bricklayers and masons, represents the skill of a master workman.

Many graduation caps were initially black or gray. According to the graduation information site Graduation Source, when color photography became the norm in the 20th century, schools began to use gowns and caps in different shades because they would show up in photographs. Schools often coordinate caps and gowns so their colors reflect their official school colors.

In addition to the cap, there is a single button at the top. Tassels hang from these buttons. At commencement, tassels are traditionally worn on the right side of the cap and then moved to the left once graduates receive their diplomas.