The London congestion charge is a fee for some motorists entering the Central London area. The organisation responsible for the charge is Transport for London (TfL). The fee was introduced on 17 February 2003. The daily charge must be paid by the registered keeper of a vehicle that enters, leaves or moves around within the congestion charge zone between 7 am and 6 pm (previously 6.30 pm), Monday to Friday. Failure to pay the charge means a fine. In February 2007, a western extension of the congestion charge came into effect, but this was ended in December 2010.

The scheme makes use of CCTV cameras to record vehicles entering and exiting the zone. Cameras can record number plates with a 90% accuracy rate through automatic number plate recognition (ANPR) technology. There are also a number of mobile camera units which may be deployed anywhere in the zone. The majority of vehicles within the zone are captured on camera. The cameras take two still pictures in colour and black and white and use infrared technology to identify the number plates. These identified numbers are checked against the list of payees overnight by computer; unrecognised plates are checked manually.