Louis Pasteur was a French scientist born on December 27, 1822. He is best known for his discoveries in the field of microbiology and for developing the process of pasteurization, which involves heating liquids to kill harmful bacteria. His work laid the foundation for the germ theory of disease, which changed the way people understood infections and hygiene. Pasteur's research also contributed to the development of vaccines, including those for rabies and anthrax. His innovative methods and dedication to science helped improve public health and safety, making him a key figure in the history of medicine and microbiology. He passed away on September 28, 1895.