Yesterday, I was at one of my clients setting up some TVs to connect their computers using HDMI. For the longest time with HDMI or hardwired connection that you either mirror your screen or extend the desktop on external displays. I didn't realize that Apple's ScreenCaptureKit allows you display a specific window or group of windows from the same app. An example of this is Google Chrome. Say you have 3 Google Chrome windows.
I only thought this applied when you share you screen on a video call such as Zoom (app) or Google Meet (browser). This also works with AirPlay as well.
When the get the picker on what you want to send to the display, the Mac sends a signal on the display to choose a window as a staging screen for the user.
This is something I haven't really encountered since I'm always on the go with my laptop in-hand. I'm always connected to the same monitors at home or at the office so the option to pick a screen doesn't really come up often.
I learned something new this week.