Hangul Day is observed in South Korea on October 9, celebrating the creation of the Korean alphabet, Hangul, which was introduced by King Sejong in 1446. The holiday commemorates the publication of the Hunmin Jeongeum, a document that outlined this new writing system. The celebration of Hangul Day began in 1928, with the date being fixed to October 9 in 1945 after the government of South Korea declared it a public holiday. Initially, the holiday was organized according to the lunar calendar, with several date changes before settling on the current fixed date. The day is marked by various activities that honor the significance of the Korean language and its script, reflecting the cultural pride associated with Hangul.