Open FaceTime or Photo Booth from your Applications folder — if you see a video preview, your Mac camera works. For a more detailed test, use an online webcam test which shows resolution, FPS, and device info. If the camera doesn't work, check System Settings > Privacy & Security > Camera and make sure your browser and apps are enabled. If the camera shows as in use by another app, close Zoom, Teams, FaceTime, and any other video apps. If it still doesn't work, reset the camera driver by opening Terminal and running: sudo killall VDCAssistant (enter your password when prompted). On newer Macs with Apple Silicon, also try: sudo killall AppleCameraAssistant. Restart your browser after running these commands. If you use an external webcam, disconnect and reconnect it.