DIAL—for DIscovery And Launch—is a simple protocol that 2nd screen devices can use to discover and launch apps on 1st screen devices.
Tablet, Phone etc. TV, Set-top box, Blu-ray etc.
For consumers, DIAL removes the pain of having to launch the required app on the 1st screen before interacting with it from their 2nd screen. DIAL does not have any significant impact on the 2nd screen's battery life and the only requirement is that both 1st and 2nd screens are connected to the same home network.
For device manufacturers, DIAL increases usage of applications on their 1st screen products (TV, set-top, Blu-ray, etc.).
For app developers, DIAL helps link their 2nd screen app to their 1st screen app without requiring a manual launch or pairing process by the user.
See the DIAL Protocol Specification for more discussion of typical use cases.