A vehicle registration plate, also known as a number plate or license plate or licence plate, is a metal or plastic plate attached to a motor vehicle or trailer for official identification purposes. All countries require registration plates for road vehicles such as cars, trucks, and motorcycles. Whether they are required for other vehicles, such as bicycles, boats, or tractors, may vary by jurisdiction. The registration identifier is a numeric or alphanumeric ID that uniquely identifies the vehicle or vehicle owner within the issuing region's vehicle register. In some countries, the identifier is unique within the entire country, while in others it is unique within a state or province. Whether the identifier is associated with a vehicle or a person also varies by issuing agency. There are also electronic license plates.

Vehicle inspection is a procedure mandated by national or subnational governments in many countries, in which a vehicle is inspected to ensure that it conforms to regulations governing safety, emissions, or both. Inspection can be required at various times, e.g., periodically or on the transfer of title to a vehicle. If required periodically, it is often termed periodic motor vehicle inspection; typical intervals are every two years and every year. When a vehicle passes inspection, often a sticker is placed on the vehicle's windshield or registration plate to simplify later controls, but in some countries—such as the Netherlands since 1994—this is no longer necessary. Most US inspection decals/stickers display the month's number and the year.