A license plate is a government-issued tag that links a vehicle to its registered owner. Every jurisdiction has its own format, colors, and rules. Some plates stay with the car for life. Others follow the driver from vehicle to vehicle.

Early plates were leather or metal discs with house numbers. Massachusetts issued the first state-issued plate in 1903. Embossed steel gave way to reflective sheeting and now digital plates that can display messages or track location. Vanity plates let owners choose letters, for a fee.

Design and rules vary widely

• European plates are long and narrow with a blue country band.
• US plates are typically 12 by 6 inches.
• Some countries require front and rear plates; others only rear.
• Special plates mark veterans, disabled drivers, or universities.

Automated readers scan plates at toll booths, parking garages, and police cars. That convenience raises privacy questions, and several jurisdictions have restricted how long plate data can be stored. A plate is simple on its face. The database behind it is not.