Stream content on a larger screen with AirPlay
Use AirPlay to stream whatever’s on your Mac mini on the big screen—or use AirPlay to send content to your Mac from an iPhone, iPad, or even another Mac. You can mirror the Mac mini screen on your high-resolution TV screen or use the high-resolution TV as a second display. To do so, connect your TV to Apple TV and make sure Apple TV is on the same Wi-Fi network as your Mac mini. You can also play web videos directly on your high-resolution TV without showing what’s on your desktop—handy when you want to play a movie but keep your work private.
Send content to your Mac from other devices. Watch videos, listen to music, and more on your Mac as they’re being played on your other devices. Mirror your iPhone or iPad on your Mac or extend its display by using your Mac as a secondary display for apps that support it, such as Keynote and Photos. Use your Mac as an AirPlay 2 speaker to stream music or podcasts to your Mac, or use it as a secondary speaker for multiroom audio. Your Mac works with any Apple device, and it’s even easier to connect if the devices share the same Apple Account.
Mirror your desktop using Screen Mirroring. Click 
Note: If your Mac supports AirPlay screen mirroring, you see an AirPlay status icon in the menu bar when an Apple TV is on the same network as your Mac. See Stream audio and video from your Mac with AirPlay.
Play web videos without showing your desktop. When you find a web video with an AirPlay icon 
Apple TV is sold separately at apple.com or your local Apple Store.
Tip: If the image doesn’t fit your high-resolution TV screen when you mirror the screen, adjust the desktop size for the best picture. Click
Learn more. To learn more about AirPlay, see Use AirPlay to stream what’s on your Mac to an HDTV. To learn more about using a second display with your Mac mini, see Connect a display to Mac mini. To troubleshoot, see the Apple Support article If screen mirroring or streaming isn’t working on your AirPlay-compatible device.