Not for Profit
A not-for-profit (also called nonprofit) organization is one set up so that no profits from its operation go to private individuals. Most SF clubs and SF cons are organized this way, either officially or practically. In the United States, nonprofit corporations are chartered by the states. (501(c)(3) status can be granted to a nonprofit corporation by the IRS.)
Note that fannish conventions are not just Not-for-Profit, but don't pay the organizers or volunteers anything other than (sometimes) reimbursing their out-of-pocket costs and membership fees. UK cons are an exception in that they issue token groats.