501(c)(3) Nonprofit Organization
A nonprofit organization approved for tax-exempt purposes under the Internal Revenue Code (IRC); typically the organization has a single major source of funding (usually gifts from one family or corporation rather than funding from many sources); 501(c)(3) organizations are either private foundations or public charities but are presumed to be private foundations unless described as public foundations in IRC Section 509(a)(1), (2), (3), or (4).