While asphalt is extremely durable, it is susceptible to cracks and potholes when exposed to elements and heavy traffic. Taking preventative maintenance measures such as sealing will preserves it's life span. 

The glue that holds the sand and stone in place quickly deteriorates, your asphalt loses oil and dries out. The only was to preserve it is by applying a driveway sealer, a cost-effective extra layer of protection to your asphalt surface.