What is a Postcode?

Postal codes used in the United Kingdom are known as postcodes (originally postal codes). They are alphanumeric and were adopted nationally between 11 October 1959 and 1974, having been devised by the General Post Office (Royal Mail).

The postcodes are alphanumeric, and are variable in length: ranging from six to eight characters (including a space) long. Each post code is divided into two parts separated by a single space: the outward code and the inward code respectively. The outward code includes the postcode area and the postcode district, respectively. The inward code includes the postcode sector and the postcode unit respectively. Examples of postcodes include SW1W 0NY, PO16 7GZ, GU16 7HF or L1 8JQ.

Postcodes have been adopted for a wide range of purposes in addition to aiding the sorting of the mail: for calculating insurance premiums, designating destinations in route planning software and as the lowest level of aggregation in census enumeration.

Outward CodeInward Code
Postcode AreaPostcode DistrictPostcode SectorPostcode Unit

What is a Postcode Area?

The postcode area is the largest geographical unit used and forms the initial characters of the alphanumeric UK postcode.[1] There are currently 121 geographic postcode areas in use in the UK and a further 3 often combined with these covering the Crown Dependencies of Guernsey, Jersey and Isle of Man. Postcode areas are subdivided into postcode districts.

What is a Post District?

A postcode district is a geographical unit used by Royal Mail. It is a subdivision of a postcode area.The postcode district is made of one or two digits or a digit followed by a letter. The outward code is between two and four characters long. Examples include "W1A", "RH1", "RH10" or "SE1P".

What is a Post Sector?

A postcode sector combines a postcode area, a postcode district and a single character. Examples include 'SE1 2', a postcode sector in London or 'G13 3', a postcode sector in Glasgow

What is a Post Town?

A post town is a required part of all postal addresses in the United Kingdom, and a basic unit of the postal delivery system. Including the correct post town in the address increases the chance of a letter or parcel being delivered on time. Post towns in general originated as the location of delivery offices. As of 2004, their main function is to distinguish between locality or street names in addresses not including a postcode.

Source: Wikipedia.com