Video mirroring duplicates your entire desktop across all connected displays.

Note: These options are available only when an external display is connected.

Option 1: Use the Screen Mirroring Menu

1. Click the Screen Mirroring icon in the menu bar
2. Click Choose Content
3. Select Entire Screen, then click Start Mirroring 

Option 2: Use a Keyboard Shortcut

To quickly mirror your Mac display to an external monitor, press Command (⌘) + F1.

Press the same keys again to return to your original display setup.