The Output Area Classification ("OAC") is the geodemographic classification released by the Office for National Statistics.

Released in 2005 and built using variables from the 2001 Census, OAC is completely free for anyone to use.

It can be either used on its own or supplemented with other information, such as income estimates, expenditure, deprivation indices or even other geodemographic classifications.

The Output Area Classification User Group provides information and support on use of the classification. For further information please visit their website which also provides links to access the data itself.