Locking your screen allows you to leave your computer unattended and prevent access to your applications and information. While your screen is locked, the screensaver runs.
To lock the screen, perform one of the following actions:
Choose System ▸ Lock Screen.
If the Lock Screen button is present on a panel, click on the Lock Screen button.
The Lock Screen is not present on the panels by default. To add it, see Section 4.3.2 ― Adding an Object to a Panel.
To unlock the screen, move your mouse or press any key, enter your password in the locked screen dialog, then press Return.