Nowadays the family name or the surname of a person is a certain component of his name and points basically to the affiliation to a family. The surname can change in the course of the life of a person. Examples for this are an adoption, marriage and separation.
Surnames have developed from the epithets. Epithets were awarded at first individually and not left bequeath. They called special qualities of a person, his origin, his occupation, were, for example, also joke names and nicknames or even day names or names of the month, they come from foreign languages or religions. Martinus Rot had, for example, remarkable red hair, Johannes Wagner the suitable occupation. Of course epithets did not stop at higher circles. Charlemagne or Heinrich the Seafarer are exemplarily mentioned at this point. Epithets already existed at early Roman times.
Only in the 8th/9th century in Upper Italian towns a surname developed from the epithet. In the 9th century a surname was bequeathed in Venice for the first time. In the 10th century it went further in southern France. Only in the 12th century this convention reached Germany, until it has asserted itself about 1600. However, the surname could still change arbitrarily (e. g. by change of the office name or by move). Legally carrying a surname was regulated only since the 18th/19th century to the duty (e. g. since 1794 in Prussia).
The nobility carried, by the way, certain surnames already since the heredity of the fiefs in 1037. This entailed of course that he could assert easier.
Epithets and surnames developed in the course of the centuries like whole languages. Therefore, a high aim of the name research is to search the origin of the name meaning. The key of the today’s German surnames is to be searched primarily in the Old High German.