When you return your rental car, a representative from the car rental company will check the vehicle for any additional damage. If any is found, the car rental company will assess the damage and charge the cost of the repairs to the customer. If you have purchased Loss Damage Waiver coverage, you will not be responsible for the additional charges, provided you haven't broken the terms and conditions of your rental agreement.
In most states, the renter is responsible for the full value of the car, plus any additional administrative fees. The amount you are liable for can differ between states, depending on the sort of damage. For example, in Illinois your financial liability for theft is limited to $2,000. In Nevada, you are not responsible for theft unless caused directly by the renter.
You should check the terms and conditions of your rental so that you understand your financial liability.
Read more about returning your rental car.