Tax deductible vs. tax exempt; charities vs. other tax-exempt entities such as trade associations; UBTI - unrelated business taxable income; Forms 990 and 990-T; self-dealing rules; Section 4940 and the 2% excise tax on investment income, 4941 and the taxes on self-dealing, 4942, 4943, 4944 and 4945; intermediate penalties and Section 4958; private foundations vs. public charities; private operating foundations; medical research organizations; types of public charities;