Diagnose the brake problem. Sponge feel / increase pedal travel? Look for leaks in the brake system. This graphical guide covers the main issues with the brakes.
Modern cars have brakes on all four wheels and are operated by a hydraulic system. The brake can be disc or drum.
The front brakes play a greater role in stopping the car than the rear brakes because the brakes push the weight of the car forward onto the front wheels.
Therefore, many automobiles have disc brakes on the front and rear drum brakes, which are generally more efficient.
All-disc braking systems are used on some expensive or high-performance cars, and all-drum systems on some older or smaller cars.