The law requires most vehicles on UK roads, including cars, to have a number plate showing the correct registration number attached to the front and back. There are a few vehicles, like tractors, that need only one plate on the back, and vehicles that don’t have to be registered with the DVLA, like bicycles, don’t need any number plates.
There are strict rules governing a number plate’s size, colour, reflectiveness and the spacing between the characters. Confusingly, the rules differ slightly depending on the registration format.
There are other rules, too. You mustn’t block the view of the plate, for instance with a bike rack or trailer. You mustn’t use stickers or tape to alter the appearance of the plate. It must be kept clean and undamaged. The rear number plate lights must be working.
If your plate doesn’t meet the rules, your car could fail its MOT. The police can fine you and even confiscate your car. If you need to replace a damaged plate, they’re available from most car parts shops.