Microbiology began with early observations of infectious diseases like malaria and the Black Plague in the 3rd century BC. The invention of the microscope in the 1600s allowed Robert Hooke and Anton van Leeuwenhoek to first observe microbes. In the late 1800s, Louis Pasteur and Robert Koch established germ theory and developed methods of isolating and growing bacteria in culture, proving that specific microbes cause specific diseases. Edward Jenner developed the first vaccine for smallpox in 1796, and later discoveries included antibiotics and vaccines for diseases like tuberculosis, plague, and polio.