[MUD] Abbrev. for "Away From Keyboard". Used to notify others
that you will be momentarily unavailable online. eg. "Let's not
go kill that frost giant yet, I need to go AFK to make a phone
call". Often MUDs will have a command to politely inform others
of your absence when they try to talk with you. The term is not
restricted to MUDs, however, and has become common in many chat
situations, from IRC to Unix talk.