Robert Koch was a German physician and microbiologist who made groundbreaking contributions to the field of bacteriology. He discovered the anthrax bacillus, tuberculosis bacillus, and cholera vibrio, and developed techniques for isolating and growing bacteria in pure cultures. Koch also formulated systematic principles known as Koch's postulates to establish causative relationships between microbes and diseases. During his career, he held professorships at Berlin University and directed the Institute for Infectious Diseases, making important discoveries related to cholera, tuberculosis, and malaria. Koch received many honors for his work, including the Nobel Prize in Physiology or Medicine in 1905.