A master cylinder is a crucial component in a vehicle's braking system. It converts the force applied to the brake pedal into hydraulic pressure, which then activates the brakes at each wheel. This process ensures that the vehicle can slow down or stop effectively when needed. Inside the master cylinder, there are typically two chambers that hold brake fluid. When the driver presses the brake pedal, a piston moves within the cylinder, pushing the fluid through the brake lines to the brake calipers or wheel cylinders. This hydraulic action allows for smooth and efficient braking performance.