An autobrake is a type of automatic wheel-based hydraulic brake system for advanced airplanes. The autobrake is normally enabled during takeoff and landing procedures, when the aircraft's longitudinal deceleration system can be handled by the automated systems of the aircraft itself in order to keep the pilot free to perform other tasks - Wikipedia
How does the aircraft "know" when is time to activate the autobrake systems on a rejected takeoff and landing?
Does it apply full brake to all the aircraft's wheels?
Is it really used by commercial jets?