In computer security, a login or logon refers to the credentials required to obtain access to a computer system or other restricted area. Logging in or on and signing in or on is the process by which individual access to a computer system is controlled by identifying and authenticating the user through the credentials presented by the user. Once a user has logged in, they can then log out or log off when access is no longer needed. To log out is to close off one’s access to a computer system after having previously logged in.