Dr. Jonas Salk was an American medical researcher and virologist who developed the first successful vaccine for polio. He is best known for his work in the 1950s, when he led a team of researchers at the University of Pittsburgh to develop the inactivated polio vaccine. The vaccine was declared safe and effective in 1955, and it has since been credited with reducing the global incidence of polio by over 99%. Dr. Salk's work has saved millions of lives and continues to be celebrated as one of the greatest medical achievements of the 20th century.