Use AirPlay to stream whatever’s on your iMac to the big screen—or use AirPlay to send content to your Mac from an iPhone, iPad, or even another Mac. You can mirror the iMac screen on your TV screen or use a 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 iMac. You can also play web videos directly on your 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 while 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 ID.
Play web videos without showing your desktop. When you find a web video with an AirPlay icon in the video, then choose an option under Match Desktop Size To.