A nickname is a familiar or affectionate name given to a person, often based on their characteristics, interests, or personality. Unlike a person's formal name, a nickname can be playful, humorous, or endearing. For example, someone named William might be called Bill or Will by friends and family. Nicknames can also reflect cultural or social contexts. In some cases, they are derived from a person's profession, hobbies, or physical traits. For instance, an athlete might be called Speedy if they are known for their quickness. Overall, nicknames serve to create a sense of closeness and identity among individuals.