A nonprofit corporation is a corporation formed to carry out a charitable, educational, religious, literary, or scientific purpose. A nonprofit corporation doesn't pay federal or state income taxes on profits it makes from activities in which it engages to carry out its objectives. This is because the IRS and state tax agencies believe that the benefits the public derives from these organizations' activities entitle them to a special tax-exempt status.
The most common federal tax exemption for nonprofits comes from Section 501(c)(3) of the Internal Revenue Code, which is why nonprofits are sometimes called 501(c)(3) corporations. For more information, see Nonprofit Basics.