2003 Pontiac Bonneville pedal goes to the floor

If it seems to take a long time to stop the car when applying the brakes, where you have to push the pedal down hard to come to a complete stop:
* This condition is often due to †brake fade, ’ which occurs when the linings become too hot. It may be caused by linings that are too thin or brakes that are overworked.
* This condition may also be caused by air in the hydraulic system, a fluid leak in master cylinder, a hose or line leak in system, and/or if the brakes misadjusted.
* This may also be an indication that the rear (or front) brakes that are not operating as designed. This requires the front brakes to work harder resulting in overheating and longer stopping distances.