The third-sector refers to the entirety of organisations that are in the economic system and rank between State and free market, with a very precise and specific role and social task.
It concerns in particular private organisations aimed at producing goods and services intended for civil society in all its forms (they especially carry out interventions in social-welfare, care and education, offering public services).

It should be noted how this expression, used for the first time in the mid 1970s in the European context, defines by negation - “third” in regard to the two traditional economic sectors, the market and the State - such a set of organisations. In the Prefazione (preface) of the voulme, edited by Agenzia per il Terzo Settore (Agency for the Third Sector), there are two quotes of authors who highlight the importance of the art of associating.

In 1835 Alexis de Tocqueville wrote: “among all the laws that rule human societies, there is one that appears clearer and more precise than all others: in order for men to remain and become civil, the art of associating has to improve with them in the same ratio the equality of conditions expands”.

In 1942 Lord Beveridge wrote: “the creation of a good society doesn’t depend on the State, but on the citizens, who act individually or in free associations (...)The happiness or unhappiness of the society we live in depends on ourselves as citizens, not on the instrument of political power that we call State”