Jonas Salk was an American medical researcher and virologist best known for developing the first effective vaccine against polio. Born on October 28, 1914, in New York City, he dedicated his career to studying infectious diseases. His polio vaccine, introduced in 1955, significantly reduced the incidence of this debilitating disease, which had caused widespread fear and paralysis. Salk's work was groundbreaking and led to the eventual near-eradication of polio in many parts of the world. He famously chose not to patent the vaccine, believing it should be available to all. Salk's contributions to medicine have had a lasting impact on public health.