Answer:
The UK equivalent of a ZIP code, only it is much more specific. It gives the location of a number of houses in a street. Together with the house number, it gives a unique location. As well as the postal service, postcodes are used in satnavs and websites for finding locations.

An example is "RG12 9PQ". In this case, RG refers to the nearest post town (which would be Reading, Berkshire), the number 12 referrs to a specific zone in the urban area or the vicinity of Reading, and the remaining charactors pinpoint a location.
First answer by Tonylevin. Last edit by Tonylevin. Contributor trust: 21 [recommend contributor recommended]. Question popularity: 1 [recommend question].