A nickname is like a special secret name that you might give to your friend instead of using their real name. It's like a special code word that only you and your friend know about. Sometimes, people give their friends nicknames based on things they like or something that reminds them of their friend.
Chad is a nickname that people sometimes use for boys named Chadwick. It's kind of like a shorter version of their real name. For example, instead of calling their friend Chadwick, they might call them Chad. It's an easier way to say their name and it sounds friendlier too!
There are so many different nicknames out there for people, and Chad is just one of them. Sometimes people like having a nickname because it feels more special and unique. But it's important to remember that not everyone likes having a nickname, so it's always a good idea to ask your friend if they're okay with you calling them by that nickname.