Stock companies are usually referred to as corporations, though all
corporations are not stock companies. A corporation is a body
consisting usually of several persons empowered by law to act as one
individual. There are two principal classes--(1) public corporations
and (2) private corporations. Public corporations are not stock
companies; private corporations usually are. Public corporations are
created for the public interest, such as cities, towns, universities,
hospitals, etc.; private corporations, such as railways, banks,
manufacturing companies, etc., are created usually for the profit of
the members. Corporate bodies whose members at discretion fill by
appointment all vacancies occurring in their membership are sometimes
called close corporations.