A VIN (vehicle identification number) is a unique code that's assigned to every car. It's usually stamped on the chassis of the car, so it can be difficult to find. However, it's important to get a VIN check done as this will give you information on the car's background, such as whether it was stolen or written off in an accident. To get a VIN check, you'll need the car's registration number and either the make and model or the V5C document reference number.