sentences:  As a security precaution, one should not rely on implicit means of logging out of a system, especially not on a public computer; instead, one should explicitly log out and wait for the confirmation that this request has taken place.Logging out of a computer, when leaving it, is a common security practice preventing unauthorised users from tampering with it.There are also people who choose to have a password-protected screensaver set to activate after some period of inactivity, thereby requiring the user to re-enter his or her login credentials to unlock the screensaver and gain access to the system.