A vehicle identification number (VIN) is the unique 17-character code assigned to a vehicle by its manufacturer. The current standard format applies to vehicles built from the early 1980s on, and NHTSA's decoding tools cover model year 1981 and later. Groups of characters in the VIN encode details such as the manufacturer, vehicle attributes, model year and the plant where it was built, followed by a serial number. Manufacturers report how their VINs are structured to NHTSA.
The VIN is usually visible through the windshield on the driver's side of the dashboard and on a label in the driver's door jamb, and it appears on the title, registration and insurance documents.
In auto transport, the VIN ties the paperwork to the physical car. It goes on the order, the dispatch sheet and the bill of lading, and the driver may check it at pickup to make sure the right vehicle is loaded. That check matters at auctions and busy dealer lots, where similar vehicles sit side by side.
For quoting, a VIN can stand in for manual entry of year, make and model, and VIN decoding fills in details that affect price, such as body style. AutoTransportVehicle.com's widget can prefill the VIN from the host page. More on auction pickups in auction vehicle transport.