Geographic Units

National geographies cover the individual nations of England, Scotland, Wales and Northern Ireland, and when combined as Great Britain and the United Kingdom.
Regional geographies can cover the individual nations of England, Scotland, Wales and Northern Ireland as a whole as well as parts of those nations, such as North West England or regions designated as Fire and Rescue Authority areas, for example.
Local authority
A Unitary Authority (UA) is a local authority responsible for local government within its area. UAs typically cover towns or cities that are large enough to function independently of a council or other authority. England has 58 UAs. Wales has 22 UAs. Scotland has 32 UAs that are called councils. Northern Ireland has 11 UAs called districts.
Census Output Area
The UK Census, undertaken every 10 years, collects population and other statistics to help plan and allocate resources. To maintain anonymity, data is presented for groups of postcodes. Each group is called an Output Area (OA) with an average of 309 residents. OAs are combined to produce larger regions such as Lower Layer Super Output Areas (LSOAs) and Middle Layer Super Output Areas (MSOAs). Learn more about UK census geography from the ONS.
LSOA / Data Zone
As described above in the section on Census Output Areas, Lower Layer Super Output Areas (LSOAs) group together Output Areas (OAs). Each OA provides the population and other statistics collected in the UK census for an average of 309 residents in England and Wales. Data Zone is the name given to a region of similar size by the Scottish Government when reporting Scottish census data.
Postcode sector
Postcodes are a compact form of geographic unit familiar to the public and businesses. A UK postcode such as PO15 5RR either identifies a single address receiving at least 500 mail items per day or a collection of 15 to 100 adjacent properties. PO15 5RR is called a unit postcode and is composed of a postcode area (PO), a postcode district (PO15) and a postcode sector (PO15 5). Learn more about UK postal geography from the ONS.
In datasets comprising attributes of individual properties, the geographic unit used to describe the property is the name of the property or its address. An example of a dataset that would use this type of geographic unit is one listing the prices paid for houses.
Other Geographies
Apart from the geographies listed on this page, the ONS uses several other geographies including Built-up Area / Built-up Area Sub-divisions and Local Education Authority (LEA) / Education and Library Boards. Learn more about these other geographies from the ONS.