IT is part of the contract you can purchase when you rent a car. If you purchase it it means that provided you have not violated the terms of the contract (say by letting someone not on the contract drive it), if the car is somehow damaged, you will not be asked to pay for the damage. Also check that you do not have to pay any excess - if you cover both you can just walk away if the hire car is damaged.
collission damage with no excess
Collision Damage Waiver
"Damage Waiver".
This would depend on the insurance that you took out with your car rental company. Check the contract that you signed. Often there is a Damage Waiver and a Theft Waiver. Usually the theft waiver is double that of the damage.
"Hertz, offers a loss damage waiver, partial damage waiver, limited loss damage waiver, liability insurance supplement, personal accident insurance, and more. These are available at time of purchase and included in daily rentals. More detail information can be found on the website."
The forthcoming insurance companies offer collision insurances: Insurance4CarHire, Auto Rental Collision Damage Waiver, Rental Cars and the Collision Damage Waiver, etc.
Usually the waiver only reduces the excess you pay.
If you don't have lost damage waiver, you might have to pay for the damages.
That's your Collision Damage Waiver -- the insurance you purchased on the rental when you rented it.
judicial, prosecutorial waiver and legislative waiver
The CDW (Collision Damage Waiver) insurance covers the following: Liability, collision, theft and other damage. This sort of insurance is offered by car rental companies.
If you agree to and sign a waiver of liability, and for example you are a pizza delivery guy. You waive (give up) any claims of damage to your car, even while using it on the job. If you have an accident you can not hold the company respponsible for damages to your car.