Section 501(c)(3) is the portion of the US Internal Revenue Code that allows for federal tax exemption of nonprofit organizations, specifically those that are considered public charities, private foundations or private operating foundations. It is regulated and administered by the US Department of Treasury through the Internal Revenue Service. There are other 501(c) organizations, indicated by categories 501(c)(1) – 501(c)(28). This discussion will focus on 501(c)(3).
Heifer International 501(c)(3) document: www2.heifer.org/dvs/shelf/documents/501c3