A voluntary association or union (also sometimes called a voluntary organization, unincorporated association, or just an association) is a group of individuals who voluntarily enter into an agreement to form a body (or organization) to accomplish a purpose.
Strictly speaking in many jurisdictions no formalities are necessary to start an association. In some jurisdictions, there is a minimum for the number of persons starting an association. Some jurisdictions require that the association register with the police or other official body to inform the public of the association's existence. This is not necessarily a tool of political control but much more a way of protecting the economy from fraud. In many such jurisdictions, only a registered association is a juristic person whose membership is not responsible for the financial acts of the association. Any group of persons may, of course, work as an association but in such case, the persons making a transaction in the name of the association are all responsible for it.