# Glossary

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#### Address Finder[​](#address-finder "Direct link to Address Finder")

A tool to extract address suggestions for a complete or partial address. See our [Address Finder demo](https://ideal-postcodes.co.uk/address-finder).

#### Alias Data[​](#alias-data "Direct link to Alias Data")

Alias data is information the public choose to use when addressing mail, but which isn’t actually required for delivery purposes.

#### Allowed URLs[​](#allowed-urls "Direct link to Allowed URLs")

A list of website addresses that can perform lookups using your API Key.

#### Closed User Group[​](#closed-user-group "Direct link to Closed User Group")

A Closed User Group is an End User’s network of businesses comprising that End User and not less than 10 Business Partners all of a single type.

#### County[​](#county "Direct link to County")

In the UK, a county is a subnational division of the country, used for the purposes of administrative or geographical demarcation.

#### Data Cleansing[​](#data-cleansing "Direct link to Data Cleansing")

Data cleansing is a solution to remove duplicates, organise data in a consistent format and correct inaccurate data.

#### Data Extraction[​](#data-extraction "Direct link to Data Extraction")

The extraction of PAF Data or any part of it for the generation of new address records in a new or existing database.

#### Delivery Point[​](#delivery-point "Direct link to Delivery Point")

The letterbox where the mail is delivered.

#### Delivery Point Suffix[​](#delivery-point-suffix "Direct link to Delivery Point Suffix")

A Delivery Point Suffix is a digit followed by a letter, which is used to identify mailboxes in the UK.

#### Dependent Street[​](#dependent-street "Direct link to Dependent Street")

A Dependent Street is included in an address when the Delivery Point is not on the main street.

#### Dependent Thoroughfare[​](#dependent-thoroughfare "Direct link to Dependent Thoroughfare")

Distinguishes a premise when a thoroughfare appears more than once in a post town.

#### Dependent Locality[​](#dependent-locality "Direct link to Dependent Locality")

Distinguishes a premise when an address thoroughfare appears more than once in the same post town.

#### Licensee[​](#licensee "Direct link to Licensee")

An End User of PAF data licensed by a Sublicensing Key. For more information, please visit our Sublicensing page.

#### Licensee Key[​](#licensee-key "Direct link to Licensee Key")

A type of API Key that an individual Licensee can use to access PAF data

#### Multiple Residence[​](#multiple-residence "Direct link to Multiple Residence")

The Multiple Residence dataset identifies and verifies premises where households share the same letter box and provides a detailed address structure for these properties. Read more in our Multiple Residence guide.

#### Not Yet Built[​](#not-yet-built "Direct link to Not Yet Built")

The Not Yet Built dataset is an additional database from Royal Mail that lists properties currently in planning or under construction. Read more in our Not Yet Built guide.

#### PAF Data[​](#paf-data "Direct link to PAF Data")

Royal Mail’s Postcode Address File (PAF) is a database containing more than 30 million postal delivery addresses and 1.8 million Postcodes. Read more on PAF.

#### Postcode[​](#postcode "Direct link to Postcode")

Combination of alphanumeric characters used as part of a postal address. Every property in the UK has a postcode assigned to it. Learn how UK postcodes are formatted.

#### Postcode Area[​](#postcode-area "Direct link to Postcode Area")

Postcode Area refers to geographic areas defined by the first or first and second alphabetic characters of the postcode.

#### Postcode Lookup[​](#postcode-lookup "Direct link to Postcode Lookup")

A tool to search UK addresses from a postcode. View and try our Postcode Lookup demo.

#### Post Town[​](#post-town "Direct link to Post Town")

Also known as the Locality. However, the post town represents the postal delivery locality and not necessarily the geographic locality.

#### Sub-Building[​](#sub-building "Direct link to Sub-Building")

A sub-building is known as a sub-premise, such as an apartment, flat, or suite.

#### Sublicensing Key[​](#sublicensing-key "Direct link to Sublicensing Key")

A type of API Key that can additionally create Licensee Keys.

#### Thoroughfare[​](#thoroughfare "Direct link to Thoroughfare")

A Thoroughfare is known as the street or road.

#### Unique Delivery Point Reference Number (UDPRN)[​](#unique-delivery-point-reference-number-udprn "Direct link to Unique Delivery Point Reference Number (UDPRN)")

A unique code used to identify a delivery point (i.e. premise) in PAF.

#### Unique Property Reference Number (UPRN)[​](#unique-property-reference-number-uprn "Direct link to Unique Property Reference Number (UPRN)")

A unique identifier for a UK addressable location, provided by Ordnance Survey.

#### Unique Street Reference Number (USRN)[​](#unique-street-reference-number-usrn "Direct link to Unique Street Reference Number (USRN)")

A unique identifier for every street in Great Britain.