A username is for two things, first it knows which email or person you are, because some people have the same password, second off, like in Roblox, your username is the name of your character/...
Weeworld.com has usernames so you don't have to give people your real name. For example my username is flysierra, which obviously isn't my real name. As the example above demonstrates, usernames are...
A user-name is a name you create or want to be identified with. Many sites will ask you what user-name you wish to be identified with when you open an account with them. It is really up to you. It...