In Windows Operating System prior to the release of Windows 8 (Consumer Preview), users can shutdown or restart the system using the option provided as part of the Start menu. And in Windows 8 users can shutdown using the option available in settings sidebar.
Navigate to the bottom or top right corner and select settings option.
From the Settings list, select Power and this would display the “Shutdown” and “Restart” option.
Another way of reach the Power option is by pressing Ctrl + Alt + Del key. The Power option will be available at the bottom right corner of the Ctrl + Alt + Del screen.