Gap Insurance is a policy rider you can get when you apply for insurance on a vehicle. If you have a loan on your automobile it's a good idea. Especially if you're involved in a motor vehicle wreck.
For instance, you buy a $20,000 and put $1,000 down. You borrow $19,000. If you're in a wreck later the property value of your vehicle may be less than your loan. In that case, the insurance company of the at fault driver would only pay the value, leaving the car wreck owner owing the lender the difference.