The Office for National Statistics (ONS) is the executive office of the UK Statistics Authority

UK Statistics Authority

The UK Statistics Authority is an independent body operating at arm's length from Government as a non-ministerial department, directly accountable to Parliament...

, a non-ministerial department which reports directly to the Parliament of the United Kingdom

Parliament of the United Kingdom

The Parliament of the United Kingdom of Great Britain and Northern Ireland is the supreme legislative body in the United Kingdom, British Crown dependencies and British overseas territories, located in London...

.
It is charged with the collection and publication of statistics

Statistics

Statistics is the study of the collection, organization, analysis, and interpretation of data. It deals with all aspects of this, including the planning of data collection in terms of the design of surveys and experiments....

 related to the economy, population and society of 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...

 at national and local levels. It functions as the office of the National Statistician

National Statistician

Directors of the UK's Office for National Statistics also hold the title of National Statistician.-Status:They are de facto Permanent Secretaries but do not use that title. As the ONS incorporated the OPCS, the Director also became the Registrar General for England and Wales...

, who is also the UK Statistics Authority's Chief Executive and principal statistical adviser to the UK's National Statistics Institute and the 'Head Office' of the Government Statistical Service (GSS).