An L-plate is a square plate bearing a sans-serif letter L, for learner, which must be affixed to the front and back of a vehicle in many countries if its driver is a learner under instruction. All new drivers in Great Britain, upon receipt of a provisional license, must display L plates at all times and be accompanied by another driver who is over 21 years of age and has held a full and valid license for the type of vehicle being driven for at least three years.