http://www.carfax.com/car_buying/vin_cloning.cfx - VIN is short for vehicle identification number, which is the unique identifier of a vehicle, similar to what fingerprints are to an individual. A V.I.N. lookup or V.I.N. search is the process in which you check the VIN to determine the used vehicle's history. A VIN check will give you information that can help you determine the actual condition of the used car.