In the early centuries, many people were illiterate and rarely traveled away from their home, so it was not necessary to have a surname. However, by the 5th century, populations grew and people began to migrate, making it necessary to distinguish one name from another.
Commonly, surnames originated from the father's first name, but have evolved through the centuries because of social class and culture.
Surnames have been derived from geographical locations, occupations, physical or character descriptions.
In the 5th through 11th centuries, common people were becoming educated and more apt to travel or relocate, deeming it necessary to distinguish one person from another.
If you are researching your genealogy, consider the fact that surname spellings may have changed over generations.
Many surnames were changed drastically when immigrants checked into Ellis Island.