a nongovernmental, nonprofit organization, with assets provided by donors and managed by its own officials and with income expended for socially useful purposes. Foundation, endowment, and charitable trust are terms used interchangeably to designate these organizations, which can be traced far back in history. They existed in the ancient civilizations of the Middle East, Greece, and Rome. Plato's Academy (c. 387 BC), for example, was established with an endowment that helped to sustain its existence for some 900 years. The medieval Christian church set up and administered trusts for benevolent purposes. The Islāmic world developed an equivalent to the foundation, entitled the waqf, as early as the 7th century AD. Merchants in 17th- and 18th-century western Europe founded similar organizations for worthy causes.

These early philanthropic forms were usually small and for local and palliative purposes. Although there are still many small foundations, the late 19th and the 20th centuries witnessed the creation of distinctive large ones that usually originated in the fortunes of wealthy industrialists. Having broad purposes and great freedom of action, including the ability by many to conduct programs worldwide, such foundations are variously categorized as: community, which have support from many donors and are located in a specific community or region; corporation-sponsored, which have increased dramatically in number, size, scope, and importance since World War II; operating, which carry out projects with their own staff; and independent, which are established by wealthy individuals and families. Most of the larger and best-known foundations in the United States and other countries have been of the last type.

James Smithson (Smithson, James) and George Peabody (Peabody, George) provided funds for the establishment in the United States of the Smithsonian Institution (1846) and the Peabody Education Fund (1867), respectively. At the turn of the century, Andrew Carnegie (Carnegie, Andrew) and John D. Rockefeller (Rockefeller, John D., Jr.) inaugurated the first of their many philanthropies. Carnegie's giving exceeded $350 million, with much of it used for the establishment of such foundations as The Carnegie Foundation for the Advancement of Teaching (1905) and the Carnegie Corporation of New York (1911). Rockefeller established the General Education Board (1902) and The Rockefeller Foundation (1913), and four generations of Rockefellers have given well over $1 billion for these entities and other philanthropic purposes.

Other American foundations of considerable size and impact were the Russell Sage Foundation (1907), The Commonwealth Fund (1918), and the John Simon Guggenheim Memorial Foundation (1925). The Ford Foundation (1936), with multibillion-dollar assets, is the largest foundation in the world. Its annual grants of millions of dollars support activities in the United States, Asia, Latin America, and Africa. Other American foundations with assets in excess of a billion dollars and supporting a broad range of activities include the W.K. Kellogg Foundation (1930), The Robert Wood Johnson Foundation (1936), The Pew Memorial Trust (1948), and the John D. and Catherine T. MacArthur Foundation (1970).

Outside the United States some of the wealthiest foundations include the Wellcome Trust, England (1936); Nuffield Foundation, England (1943); Juan March Foundation, Spain (1955); Calouste Gulbenkian Foundation, Portugal (1956); Alfried Krupp von Bohlen und Halbach Foundation, Germany (1967); J.W. McConnell Family Foundation, Canada (1967); and the Toyota Foundation, Japan (1974).

The large modern foundations have expended most of their funds for activities in the fields of education, social welfare, science, health, religion, conservation, international relations, and public policy. Some foundations have been reluctant to publicize their activities. Others, especially the larger ones, provide reports on their operations and, in recent years, have been instrumental in establishing such informational and archival organizations as The Foundation Center, U.S. (1956), the Foundation Library Center of Japan (1985), and the European Foundation Centre, Belgium (1989).