Why do some countries have different number plate colours?

Different number plate colours are often used to make certain vehicle types or registration categories easier to identify at a glance. Rather than reading the registration number itself, police, border authorities and other road users can quickly distinguish between different types of vehicles based on the colour scheme.

For example, some countries use different coloured plates for commercial vehicles, diplomatic vehicles, government vehicles, temporary registrations or public transport. In other cases, colours form part of the country's standard registration design, such as the yellow number plates used in the Netherlands.

When identifying international number plates, colour can be a useful clue alongside the vehicle country code, registration format and national identifiers, but it should not be relied upon in isolation.