In a traditional car, the brake pedal is physically connected to the hydraulics through a master cylinder. Many modern and electric vehicles instead use brake-by-wire. Here is what brake-by-wire means and how it works.
Electronic instead of purely mechanical
In a brake-by-wire system, pressing the pedal sends an electronic signal to a control unit rather than directly pushing hydraulic fluid. The computer then decides how much braking to apply and commands actuators at the wheels - the pedal becomes an input sensor, not a direct hydraulic plunger.
Why cars use it
Brake-by-wire lets the car blend friction braking with regenerative braking seamlessly - essential in EVs and hybrids; see how regen braking works. It also enables features like precise ABS, stability control, and automatic emergency braking, since the computer can modulate each wheel instantly.
Is there still a hydraulic backup?
Most brake-by-wire systems keep a hydraulic backup or fallback so the friction brakes still work if the electronics fail - the base disc brakes are still there; see how disc brakes work. Full "dry" brake-by-wire with no hydraulic link is still rare and heavily redundant.
What it means for service
The pads, rotors, and calipers are still conventional wear parts you can service normally - see do EVs have brake pads - though the system may need a scan tool to bleed or reset. Fit quality pads and hardware as usual.