Knob Knowledge, also known as Fourth-Class Knowledge, is a collection of Citadel lore and trivia gathered by college librarians over the years. It grew out of the tradition of upper-class cadets asking knobs (freshmen) questions to enhance their knowledge of The Citadel and its history, and to build esprit de corps. Today, freshmen are only required to know what is specifically stated under Fourth-Class Knowledge in The Fourth-Class System Manual, also known as the Red Book.