The National Statistics Socio-economic Classification (often abbreviated to NS-SEC) is the primary social classification in the United Kingdom. Its first major use was on the 2001 UK census. The classification replaced two previous social classifications: Socio-economic Groups and Social Class based on Occupation.
The full version of NS-SEC has 17 main categories and is collapsible down to three categories. Only the three-category version is intended to represent any form of hierarchy. The version intended for most users (the analytic version) has eight categories: