Glossary

The terms used across the site, in the sense the source data uses them.

Census: The count of the population taken every ten years in the United Kingdom, in years ending in 1. There was no census in 1941 because of the war. The 2021 census covered England and Wales; Scotland held its own in 2022.
Administrative county: The unit a county council governed before the 1974 reform. In 1961 it excluded the county boroughs inside its area, which is why figures for a county and for the ground it covers can differ.
County borough: A town that ran its own affairs independently of the surrounding county before 1974. Birmingham, Coventry, Newcastle upon Tyne and Norwich were among them. Figures on this site sum the districts within a county, so county boroughs are included.
Mid-year population estimate: The Office for National Statistics estimate of population at 30 June each year, published between censuses. Used here for 1981 onward. It is an estimate, not a count, and so is a different instrument from a census figure.
Usual resident: A person who lives in an area for twelve months or more, or intends to. The basis on which census population is counted.
Tenure: Whether a household owns its home, rents it, or occupies it some other way. Owner-occupied means the household owns outright or with a mortgage.
Occupancy rating: A 2021 census measure of whether a household has more or fewer rooms than a standard suggests it needs. It is not the same as persons per room, which is why the two are not compared on this site.
Country of birth: Where a resident was born, regardless of nationality or citizenship. Residents born outside the UK is the total population minus those born in the United Kingdom.
Open Government Licence: The licence under which most UK public sector information is published. It permits copying, publishing and adapting the information, including commercially, provided the source is acknowledged.
Red List Index: A measure of how close a group of species is to extinction, published by the United Nations as Sustainable Development Goal indicator 15.5.1. A value of 1 means no species is expected to go extinct in the near future; 0 means all have.
Estimate badge: Shown next to a figure that is a compiled estimate rather than a count. World and continent figures always carry it.
Approximate area badge: Shown where modern authorities have been aggregated to stand in for a historic county, so the figure is indicative rather than like for like.