AirPlay Mirroring works similarly to DLNA (Digital Living Network Alliance). There is a host device, the device acting as a server (such as an iPad), and a display device, acting like a client, or visual portal. The concept is similar to a computer tower transmitting information to a monitor, only without cables.
When you stream from your device, the devices continuously exchange information through an invisible network of radio waves, which are then interpreted through wirless adapters in each device. These data transactions allow you to see changes made on the host device in real time.