Pseudonym
Many people on the Internet use pseudonyms. There are many names for these pseudonyms, including user-names, user IDs and handles. These pseudonyms help people stay anonymous on the internet, and they also protect people from identity theft and phishing. When people log into an account on sites like Wikipedia, MySpace or Facebook, their user-name helps identify them without entering their real name. If people used their real name instead of a user-name, it would create confusion for two people with the same name. Usernames make this simple, because people create their own user-names. Also, if someone used their real name, it would make it easier for people to guess their passwords and for other people to find them in real life.