User

"A user is a person who uses a computer or network service. A user often has a user account and is identified by a username (also user name). Other terms for username include login name, screen name (also screenname), nickname (also nick), or handle, which is derived from the identical Citizen's Band radio term. Users generally use a system without the technical expertise required to understand it fully, while power users use advanced features of programs. In projects in which the actor of the system is another system or a software agent, it is quite possible that there is no end-user for the system." [User (computing). Wikipedia]