A license plate is a metal or plastic plate that is attached to the front and back of a vehicle. It is used to identify the vehicle and its owner. The term 'license plate' is often shortened to 'TAG, ' which is the three-letter solution to this crossword puzzle. License plates are issued by state governments and are typically required for all vehicles registered in the state. They are used to track the vehicle's registration and ownership, as well as to collect taxes and fees.