a.k.a. userID

The name you use to access certain programs, Web sites, software, or networks. A username is like a handle for a user on the Internet and is commonly left up to the user to select (although most systems will not allow the same username to be assigned to two different people). Usually it's the first part of your e-mail address, before the @ sign, or it could be the nickname you use in a chat room.

See also : password  
NetLingo Classification: Online Jargon