Power button

Press the Power button to turn on your iMac.

Choose Apple menu > Shut Down to turn off your Mac, or choose Apple menu > Sleep to put it to sleep.

You can also lock your Mac by pressing the Touch ID button on your Magic Keyboard. When you first start up or restart, you need to log in by typing your password. After you set up Touch ID, you can authenticate with a touch instead of typing your password (after your first login), and use Touch ID for Apple Pay purchases.