What is Screen Mirroring?

Screen mirroring duplicates your phone or laptop display onto a TV in real time — everything on the small screen appears on the big one, notifications included.

Casting a specific app is usually better for video (full quality, phone stays free), but mirroring is the universal fallback for apps without a cast button, photos, and presentations. Android uses Smart View/Cast, Apple uses AirPlay, Windows uses Miracast ("Project").