King Sejong was the fourth king of the Joseon Dynasty in Korea, ruling from 1418 to 1450. He is best known for creating the Korean alphabet, called Hangul, which made reading and writing accessible to the common people. Before Hangul, Koreans used complex Chinese characters, which were difficult for many to learn. In addition to his work on the alphabet, King Sejong promoted science, agriculture, and culture. He established the Hall of Worthies, a group of scholars who helped him develop new inventions and improve farming techniques. His reign is often considered a golden age in Korean history, marked by innovation and progress.