The first person to discover the vaccine for smallpox was Edward Jenner. In 1796, Jenner conducted his groundbreaking experiment by inoculating a young boy with cowpox, a less severe disease, to confer immunity against smallpox. This method laid the foundation for modern vaccination practices, demonstrating that exposure to a related pathogen could prevent a more severe illness. Jenner's discovery is considered a pivotal moment in the field of immunology, significantly reducing the incidence of smallpox, which ultimately led to its global eradication in 1980.