The braking system in a vehicle is a fairly simple design to pick apart. Consisting of a caliper, two brake pads, and a rotor for each wheel, fluid is sent to each caliper from the master cylinder whenever the brake pedal is pressed via hydraulic lines. A piston inside the caliper is activated and the caliper then squeezes the rotor between the inner and outer brake pad. This results in the friction between the brake pads and the wheel and your vehicle slows down.