In internet slang, a luser is a painfully annoying, stupid, or irritating computer user. The word luser is often synonymous with lamer. In hackish, the word luser takes on a broader meaning, referring to any normal user (i.e. not a guru), especially one who is also a loser (luser and loser are pronounced the same). Also interpreted as a layman user as opposed to power user or administrator.

This word was coined around 1975 at MIT. Under ITS, when you first walked up to a terminal at MIT and typed Control-Z to get the computer's attention, it printed out some status information, including how many people were already using the computer; it might print "14 users", for example. Someone thought it would be a great joke to patch the system to print "14 losers" instead. There ensued a great controversy, as some of the users didn't particularly want to be called losers to their faces every time they used the computer. For a while several hackers struggled covertly, each changing the message behind the back of the others; any time you logged into the computer it was even money whether it would say "users" or "losers". Finally, someone tried the compromise "lusers", and it stuck. Later one of the ITS machines supported "luser" as a request-for-help command. ITS ceased to be used mid-1990, except as a museum piece; the usage lives on, however, and the term "luser" is often seen in program comments and on Usenet.

A Luser Attitude Readjustment Tool (LART) or cluebat or clue stick or clue by four is "something large, heavy and painful, used to respond appropriately to particularly annoying lusers".

It is also a common IRC command to get the number of users connected to a server or network.

See also

• Any key
• BOFH
• Newbie