This document discusses Bacillus anthracis, the bacterium that causes anthrax. It begins by classifying Bacillus anthracis and other related bacteria. It then outlines the key discoveries and developments regarding B. anthracis, including being the first bacterium observed under a microscope, isolated in pure culture, and shown to cause disease. The document goes on to describe the morphology, cultural characteristics, biochemical reactions, resistance, pathogenicity, laboratory diagnosis, epidemiology, prophylaxis, treatment, and role in bioterrorism of B. anthracis. It also discusses the three forms of anthrax disease in humans and their symptoms.