Public charities, also known as 501(c)(3)s by the IRS, must support themselves as they work on fulfilling their missions. Much of that support must come from the public.

To receive public funding charities must run fundraising campaigns directed toward individual donors. Nonprofits can also apply for foundation grants. Nonprofits can also charge fees for services, sell merchandise, and sell tickets for performances. There are specific rules for ow much income may be generated from charging for services. That revenue is called "earned" income, and many charities benefit from establishing these income sources.