noun (used with a singular verb)
the study of the origin, history, and use of proper names.
Onomastics or onomatology is the study of proper names of all kinds and the origins of names. The word is derived from the Greek word, "onoma," meaning name.
Members of royal families still use single names. A few celebrities, such as Madonna or Prince, also adopted single names to further their careers. The rest of us use two or more names to reduce confusion in identifying individuals. In most of the world, hereditary family names, or surnames, have become the norm. Many names originally were based on a person's physical characteristics, place of residence, occupation, or other distinguishing characteristics. As the centuries passed, the surnames have remained although those who carry the name today usually bear little resemblance to the ancestral namesake's original unique characteristics.
Most Western cultures use the name order of "first name" for personal name and "last name" or "surname" for family name while much of the rest of the world uses the opposite order: family name before the personal name.