Magic Keyboard
The wireless Magic Keyboard included with your iMac has built-in features that make it easy to enter emoji, switch keyboard languages, lock your iMac, and perform many system functions with the touch of a key. The Magic Keyboard with Touch ID also lets you use a fingerprint to sign in and make purchases using Apple Pay.
To connect your Magic Keyboard to your iMac, see Connect accessories to your iMac.
Turn the keyboard on or off. Slide the on/off switch on the back edge of the keyboard to turn it on 
(so green is visible) or off. If your keyboard isn’t recognized by your iMac, connect it to your iMac with the included USB-C to Lightning Cable to pair it, then disconnect the cable to use it wirelessly. Use the same cable to charge your keyboard.
Lock your iMac. Quickly press Touch ID or the Lock key 
(Magic Keyboards that don’t have Touch ID have a Lock key instead). To unlock your iMac, lightly touch Touch ID, or press any key and type your password.
Set up Touch ID. If your keyboard has Touch ID, you can use your fingerprint to unlock your iMac and make purchases from the App Store, Apple TV app, and Apple Books, and on websites using Apple Pay. If you don’t set up Touch ID when you set up your iMac, you can do it later in the Touch ID & Password settings in System Settings. For more information about Touch ID, see Set up your iMac. For information about Apple Pay, see Use Wallet and Apple Pay in the macOS User Guide.
Use Touch ID. Place your finger lightly on Touch ID. When you first start up or restart your iMac, you need to type your password to log in to your iMac. After that, whenever you’re asked for your password to unlock the screen or make purchases, you can use Touch ID. You can also use your fingerprint to switch from another user’s account to your own if you set up fast user switching for your iMac. For more information, see Use Touch ID on Mac in the macOS User Guide.
Set keyboard settings. To specify options for your keyboard and the Function (Fn)/Globe key 
, open System Settings, click Keyboard in the sidebar, and choose options to change your keyboard or input source, show emoji and symbols, start dictation, or define functions.
Use emoji or switch keyboard languages. Press to switch to a different keyboard. Press repeatedly to cycle through emoji options or other languages you specify in Keyboard settings, or press twice quickly to start dictation (if you set that preference).
Use function keys. The function keys on the top row provide shortcuts for these common system functions:
Brightness (F1, F2): Press
or 
to decrease or increase the brightness of the screen.Mission Control (F3): Press
to view what’s running on your iMac, including all your spaces and open windows.Spotlight Search (F4): Press
to open Spotlight and search for something on your iMac.Dictation/Siri (F5): Press
to activate dictation—you can dictate text wherever you can type (for example, in Messages, Mail, Pages, and other apps). Press and hold to activate Siri, then immediately speak your request.Do Not Disturb (F6): Press
to turn Do Not Disturb on or off. When Do Not Disturb is on, you won’t see or hear notifications on iMac, but you can view them in Notification Center.Media (F7, F8, F9): Press
to rewind, 
to play or pause, or 
to fast-forward a song, movie, or slideshow.Mute (F10): Press
to mute the sound from the built-in speakers or headphone jack.Volume (F11, F12): Press
or 
to decrease or increase the sound volume from the built-in speakers or headphone jack.
Use alternate functions. Function keys may perform actions for specific apps or may have alternative functions—for example, the F11 key can also hide all open windows and show the desktop. To trigger the alternative function associated with the key, press and hold the Fn key while you press a function key.
Use keyboard shortcuts. You can press two or more keys at the same time to quickly do things on your iMac that you’d normally do with a trackpad, mouse, or other device. For example, press Command-C to copy selected text, then click where you want to paste the text and press Command-V. For a list of commonly used keyboard shortcuts, see Keyboard shortcuts on your Mac. If you’re new to the Mac, you might also be interested in Are you new to Mac?.
Note: Touch ID and the function keys work as described above for any Mac with Apple silicon and macOS 11.3 or later.