The National Statistics Socio-economic Classification (often abbreviated to NS-SEC) is the primary social class

Social class

Social classes are economic or cultural arrangements of groups in society. Class is an essential object of analysis for sociologists, political scientists, economists, anthropologists and social historians. In the social sciences, social class is often discussed in terms of 'social stratification'...

ification in the United Kingdom

United Kingdom

The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

. Its first major use was on the 2001 UK census

United Kingdom Census 2001

A nationwide census, known as Census 2001, was conducted in the United Kingdom on Sunday, 29 April 2001. This was the 20th UK Census and recorded a resident population of 58,789,194....

. 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

Hierarchy

A hierarchy is an arrangement of items in which the items are represented as being "above," "below," or "at the same level as" one another...

. The version intended for most users (the analytic version) has eight categories:

1. Higher managerial
   Management
   Management in all business and organizational activities is the act of getting people together to accomplish desired goals and objectives using available resources efficiently and effectively...
   
    and professional
   Professional
   A professional is a person who is paid to undertake a specialised set of tasks and to complete them for a fee. The traditional professions were doctors, lawyers, clergymen, and commissioned military officers. Today, the term is applied to estate agents, surveyors , environmental scientists,...
   
    occupations
2. Lower managerial and professional occupations
3. Intermediate occupations (clerical, sales, service)
4. Small employers and own account workers
5. Lower supervisory and technical
   Technology
   Technology is the making, usage, and knowledge of tools, machines, techniques, crafts, systems or methods of organization in order to solve a problem or perform a specific function. It can also refer to the collection of such tools, machinery, and procedures. The word technology comes ;...
   
    occupations
6. Semi-routine occupations
7. Routine occupations
8. Never worked and long-term unemployed

The three-category version is reduced to following categories:

1. Higher occupations
2. Intermediate occupations
3. Lower occupations