A surname is a person’s last name, or family name. Smith is a popular surname in the U.S., while Dieng is a popular surname in Senegal.
Your surname is your last name. A surname can be Smith, Jones, Johnson, Giacometti — any name that someone gets from their family. The word surname derives from sur “above" + name. The term surname was first used by feudal lords, who adopted the name of their property as their family name. A surname can be derived from a place name (e.g., London) or a trade (e.g., Schneider means "tailor" in German).