The voluntary sector or community sector (also non-profit sector or "not-for-profit" sector) is the sphere of social activity undertaken by organizations that are not for profit and non-governmental. This sector is also called the third sector, in reference to the public sector and the private sector. Civic sector is another term for the sector, emphasizing the sector's relationship to civil society.
Discourse on the "third sector" began in the 1970s in France as a result of the crisis in the welfare state.
In Japan since the 1980s, the third sector (第三セクター daisan sekutā) refers to joint corporations invested both by the public sector and private sector.
In rail transport terms, a third sector railway line is a short line or network of lines operated by a small operator jointly owned by a prefectural/municipal government and smaller interests. Third sector lines are generally former JR Group (or JNR before 1987) lines that were divested from the national company.
The Cabinet Office of the British government until 2010 had an Office of the Third Sector that defined the "third sector" as "the place between State and (the) private sector." The Conservative/Liberal Democrat Coalition Government renamed the department the Office for Civil Society. The term third sector has now been replaced in Government usage by the term Civil Society or more usually the term Big Society, which was devised by political advisers and which featured prominently in the Conservative Party's 2010 election campaign.