A surname can also be called a last name or a family name. It derives in French usage in the 14th century from the term surnom which means "additional name." Initial use of the term in France may be more analogous to nickname, than it is to family name. In Middle English, the term sirename is thought a corruption of surnom and likely stood for the way in which most Westerners use surname in present day. It was the name of the father, given to the child upon birth. Last name is a little bit deceptive in use, since in numerous Asian cultures, a family name occurs before a last name.
Surnames are used in various forms throughout many of the world’s cultures, but each culture may define how a surname is derived or used. In much of Western Europe and the US, the surname is the last name of the father, or in the absence of married parents, the last name of the mother. Even when women retain their surnames upon marriage, they frequently will still give their children the last name of the children’s father. A few children get hyphenated names, but this is relatively uncommon and tends not to survive more than a generation or two. Two adults with hyphenated names who have children would have to give their children four surnames.
The use of the surnames was not common in much of the Western world until about the 10th century, and likely dates to the Vikings use of them. Record of use exists much farther back in Asia. In China, the first surname may have been Fu, and the tradition begun with Emperor Fu Xi in about 2850 BCE. You won’t find much record of surname usage in Ancient Greece, Rome or in Biblical literature. Sometimes people were identified by where they came from, and tradition of surnames that date back to a geographical location reflects in many of the family names today.
In fact, many surnames can be traced to several different identification methods; they may reflect occupation, area of birth, physical or personal traits, names of animals, or religious names. A number of surnames, particularly from Northern Europe end in “sen,” “sian” or “son,” which tends to mean son of. In biblical writings, though surnames aren’t common, the tradition of identifying oneself by parental origin or ancestral lineage is.
The most common surname in the world today is not Smith, but Chang. In the US, Smith is the most common last name, followed by Johnson, Williams, Jones, and Brown. Having one of the more common family names makes it very difficult to trace lineage, given the proliferation of the name amongst unrelated people. It’s much easier to trace heredity when you have an uncommon surname. Rules for determining surnames are very complex through much of the world, and even include things like adding different word endings to indicate masculine or feminine children, or tracing family lineage through mothers rather than fathers. Each culture determines how surnames will be used, and even within that usage there are numerous exceptions and individual cases.