A family name, surname, or last name is the part of a person's name that indicates to what family he or she belongs. Until the 12th century, most people throughout the world did not use or have a family name, and they were called by the single name they had (which was called a "first" or "given name" only after family names came into use). One of the most accepted theories for the origin of surname use attributes their introduction to the Normans and the Domesday Book of 1086.