When pressure is applied on the brake pedal, the hydraulic system transfers that pressure to the callipers, causing friction to be generated between the brake pad and disc.
When your brake pads apply pressure to the rotor, which is directly connected to each wheel. This pressure creates the friction needed to slow or stop your vehicle.
The brake shoe carries the brake lining, which is riveted or glued to the shoe. When the brake is applied, the shoe moves and presses the lining against the inside of the drum.
The wheel cylinder is a part of the brake drum assembly. Its job is to press the brake shoes against the brake drum. This creates the friction needed to slow your vehicle.
The brake master cylinder is activated by applying pressure to the brake pedal, and effort is minimized by the brake booster.