How to shutdown or restart my Windows computer via command prompt

Microsoft Windows offers several ways to shut down or restart your computer, one of which is via the command prompt.
To access the command prompt window from Vista or Windows 7:

1. Go to the Start menu
2. Type cmd in the Search field
3. Press Enter

On a Windows XP computer:

1. Click the Start menu
2. Choose Run
3. Type cmd
4. Press Enter

From an open command prompt window, you can type shutdown, and then the option you wish to execute.
To shut down your computer type: shutdown /s
To restart your computer type: shutdown /r
To log off your computer type: shutdown /l
For a complete list of options type: shutdown /?