Automatic number plate recognition is a government surveillance method that relies on optical scanning equipment to read car number plates as the vehicles travel on public roads. Car number plates, issued by national licensing agencies such as the Driver and Vehicle Licensing Agency (DVLA) in the UK, are unique vehicle identifiers that relate a car owner, their address and vehicle to each other. Number plate recognition methods are typically used to track down criminals, road traffic offenders, to monitor road tax compliance and to find stolen vehicles.

Automatic number plate recognition (ANPR) is also known as automatic licence plate recognition (ALPR), automatic vehicle identification (AVI), car plate recognition (CPR) or licence plate recognition (LPR). In the UK, ANPR was first developed in the 1970s and rolled out over the UK from the M1 motorway and onwards to other major roads.

ANPR can also be used to monitor cars for tolling purposes. In London, for example, the congestion charge can be paid automatically, with cameras able to check cars automatically for their (non)-payment. Car number plates can be read both from the front or the back of the car.

So as to be able to be used throughout the whole 24 hours and in as many atmospheric conditions as possible, most ANPR systems use infrared technology. The technology used can also read number plates on cars driving at considerable speed.  A common complaint against ANPR systems is that they amount to state surveillance of citizens on a mass scale.