There are a number of places in a car where a belt drive is applicable, including the water pump, power steering pump, and in a variety of other accessories. In older model cars each of these would be driven by its own entirely separate mechanism, but in modern cars all these systems are run by a single belt drive, referred to as a serpentine belt. Therefore, if this belt breaks it can mean a number of devices stop working simultaneously, putting the vehicle completely out of action.
When a belt drive fails the symptoms are generally easy to detect, meaning that the complete failing of one is rare. Simply inspect the belt closely and look for cracks, tears or lesions. Small lesions are not a problem, but those that look deep will soon expand and eventually result in the belt snapping. It is best to replace a belt before the lesions worsen and render the vehicle grounded. If there is a noticeable shrieking noise from the car when starting it, especially on cold mornings, this is a sign that the belt is loose.
If your vehicle has a serpentine belt drive and it breaks there is a chance the engine will be damaged from overheating, so it is essential to keep an eye on the belt at regular intervals. Keep in mind that every belt has a limited lifespan and will wear eventually, with some makes wearing out faster than others. Replacing the belt on belt drives is not overly difficult and can be managed by most DIY mechanics. However, be sure to take special note of where a belt belongs before removing it for replacement. Drawing a reference diagram is recommended.