Most cars have a water pump, a power-steering pump and various accessories that are driven by belts. On older cars, each part gets its own belt. On most modern cars, they're all driven by one belt, called a serpentine belt.
Like tires and fluids, belts wear out from use, age and heat. When they fail, whatever they were powering fails with them. Since the serpentine belt powers so many parts, that's a lot of the car. Without the water pump, the engine will rapidly overheat. The alternator quits producing amps, the power steering is without power. Very suddenly, you're not going anywhere.
Belts hardly ever fail while you're at the service station. They much prefer dark roads, far from help. To avoid this, have your belts inspected regularly - especially if they're 4-5 years old or have 50,000 miles on them. Replace the serpentine belt if it is worn.
Have a concern about your belts? Let the pros at any of our stores take a look at them for you. While you're here, we'll also make sure your tires have the right pressure.