The tax code contains at least 30 different categories of nonprofits. What we think of as “charities” are typically organized under Section 501(c)(3). That section exists for “charitable” and “religious” organizations, and it is where one finds organizations such as churches, the Red Cross, the American Cancer Society and so on. Section 501(c)(4) is traditionally reserved for advocacy organizations. The National Rifle Association, the Sierra Club, Planned Parenthood Action Fund, and the Brady Campaign to Prevent Gun Violence are 501(c)(4)s.