Feb 22, 2021 This post contains references to products from one or more of our advertisers. We may receive compensation when you click on links to those products. Terms apply to the offers listed on this page. For an explanation of our Advertising Policy, visit this page. Before I bought a used car last year, I’m not sure I’d ever heard of a vehicle identification number (VIN). But between shopping for a car, reviewing accident and service history reports and getting the vehicle insured, registered and inspected, I became very familiar with this 17-character string of digits and letters. A car’s VIN is basically its social security number — an alphanumeric thumbprint, if you will — and no two vehicles have the same identifying code.