Master cylinders are hydraulic actuators converting mechanical force from the brake pedal into hydraulic pressure. Located within the vehicle’s brake system, they house pistons and reservoirs to generate and store brake fluid under pressure. Internal construction typically features single or dual-circuit designs for redundancy, with varying bore sizes impacting pedal feel and hydraulic ratio. Key components include the piston assembly, primary and secondary sealing surfaces, and fluid compensation ports. Modern units often integrate anti-lock braking system (ABS) module connections for seamless system integration.