Iconography. The study of pictures or images (icons) and their meaning. Numismatics contributes greatly to iconography; frequently portraits, scenes of buildings and statues are known only from the images appearing on coins and medals. Many ancient or medieval rulers are known only by their numismatic portraits and portraiture. Iconography as a tool of the cataloger is used to attribute undated coins, particularly ancient Greek, to an approximate time by comparison of images found on coins to related and known objects. The study of iconography is an important function of art history.