A standard deductible applies to any damage to the rental car. This is the amount, up to a set maximum, that you may have to pay in cases such as a flat tire, damage you cause yourself, or damage caused by a third party. If there is no damage, you will not be charged.
The deductible amount is reserved on your credit card when you pick up the car. In many cases, this amount is part of the security deposit. Avis also offers the option to reduce the deductible.