username - Computer Definition
Synonymous with user ID. See user ID.
The name people use to identify themselves when logging into a computer system or online service. In most situations, both a username (user ID) and password are required. In an Internet e-mail address, the username is the left part before the @ sign. For example, KARENB is the username in email@example.com. AOL calls a username a "screen name." A Username Can Be an E-Mail Address For some sites, a person's e-mail address can be used instead of making up a name. However, sometimes, a username must be the e-mail address (see below).