A windshield has two layers. The outer layer is to protect you from the outside elements, allowing you to travel from point A to B safely. The inner layer protects you if anything were to happen to shatter the outer layer. Windshields are designed with an anti-shatter element to ensure your safety. However, acquiring additional cracks without repair can be detrimental to the efficacy of your windshield.
 

Depending on the placement and severity of the break or crack in the glass, moisture can get into the cracks and further compromise the integrity of your windshield. A windshield’s job is to protect you from the outer elements. When a crack occurs, the initial layer of protection is compromised, therefore making it less reliable the next time that a crack occurs. When such structural integrity has been altered, it puts you at further risk of injury if an accident were to occur. In the event that an accident does occur, your airbags could be deemed unreliable as they deploy and push off the windshield so they can protect the passengers. Windshield damage can ultimately prevent them from working and deploying properly.