The document discusses three types of anthrax - gastrointestinal, pulmonary, and cutaneous - defined by their transmission route. It also notes that anthrax is sometimes used in bioterrorism and that after 9/11, demand increased for the anthrax vaccine used by U.S. troops, but the sole supplier was failing to meet its contract with the military, causing a shortage. The most common type is cutaneous anthrax, which has the lowest mortality when treated with antibiotics.