User account

Users in a computing context refers to one who uses a computer system. Users may need to identify themselves for the purposes of accounting, security, logging and resource management. In order to identify oneself, a user has an account (a user account) and a username (also called a screen name, handle, nickname, or nick on some systems), and in most cases also a password (see below). Users employ the user interface to access systems, and the process of identification is often referred to as authentication.

Users are also widely characterized as the class of people that uses a system without complete technical expertise required to fully understand the system. In most hacker-related contexts, they are also called real users. See also End-user (computer science).

A computer user is similar to the user in telecommunications, but with slight semantic differences. The difference is comparable to the difference between end-users and consumers in economics.

For instance, one can be a user of (and have an account on) a computer system, a computer network or have an e-mail account.

Semantics
A user account allows one to authenticate to system services. It also generally provides one with the opportunity to be authorized to access them. However, authentication does not automatically imply authorization. Once the user has logged on, the operating system will often use an identifier such as an integer to refer to them, rather than their username. On Unix systems this is called the user identifier or user id.

Computer systems are divided into two groups based on what kind of users they have:


 * single-user systems do not have a concept of several user accounts
 * multi-user systems have such a concept, and require users to identify themselves before using the system. Systems for users.