Wikipedia
In the automotive industry, brake-by-wire technology is the ability to control brakes through electrical means. It can be designed to supplement ordinary service brakes or it can be a standalone brake system.
This technology is widely used on all hybrid and battery electric vehicles, including the Toyota Prius. Brake-by-wire is also common in the form of the Electric Park Brake which is now widely used on mainstream vehicles.
The technology replaces traditional components such as the pumps, hoses, fluids, belts and vacuum servos and master cylinders with electronic sensors and actuators. Drive-by-wire technology in automotive industry replaces the traditional mechanical and hydraulic control systems with electronic control systems using electromechanical actuators and human-machine interfaces such as pedal and steering feel emulators.
Some x-by-wire technologies have been already installed on commercial vehicles such as steer-by-wire, and throttle-by-wire. Brake-by-wire technology has been widely commercialized with the introduction of Battery Electric Vehicles and Hybrid Vehicles. The most widely used application by Toyota in the high volume Prius was preceded by the GM EV1, the Rav4 EV, and other EVs where the technology is required for regenerative braking. Ford, General Motors, and most other manufacturers use the same general design, with the exception of Honda, who designed a notably different design.