What is a 501(c)(3)?
A 501(c)(3) is commonly referred to as a charity; it doesn't need to pay taxes on contributions it receives, and its donors can generally make tax-deductible contributions. Examples of 501(c)(3) organizations include churches, professional organizations, research organizations, educational entities, and welfare agencies. Some of the larger 501(c)(3) organizations in the United States include the New York Public Library, St. Jude Children's Research Hospital, the Nature Conservancy, and Catholic Charities USA.
Because they're exempt from paying taxes, the nonprofits have several limitations on their activities. A 501(c)(3) can't participate fully in political processes, can engage in only very limited lobbying, is required to pay taxes on unrelated business income, cannot excessively benefit private interests, including board members and employees, and has to file annual reports with the IRS while making them available to the public.