An autograph book is a book for collecting the autographs of others. Traditionally they were exchanged among friends, colleagues, and classmates to fill with poems, drawings, personal messages, small pieces of verse, and other mementos. Their modern derivations include yearbooks, friendship books, and guest books. They were popular among university students from the 15th century until the mid-19th century, after which their popularity began to wane as they were gradually replaced by yearbooks.