Hangeul Proclamation Day, known as 'Hangeul Day' in South Korea, is a significant national holiday that commemorates the invention and the proclamation of Hangeul, the native alphabet of the Korean language. The holiday falls on the 9th day of the 10th month of the lunar calendar, which is October 9 in the Gregorian calendar. This day is celebrated grandly by Koreans every year as a mark of their linguistic pride and cultural heritage.

The invention of Hangeul is credited to King Sejong the Great and his scholars in the 15th century. The creation of Hangeul emerged as a democratic move to spread literacy among the common people who had difficulties reading and writing using the Chinese characters that were prevalent at that time. Therefore, Hangeul Proclamation Day stands not only as a testament to an important linguistic achievement but also as a beacon of historical importance signifying the democratization of literacy.

Hangeul Day was officially recognized as a national holiday in South Korea in 1945. On this day, a variety of events are held nationwide, such as Hangeul writing competitions, exhibits showcasing the history and value of the Korean alphabet, and cultural festivities. Educational institutions organize special sessions to educate students about the significance of Hangeul. The holiday is meant to encourage the South Korean people to reflect on the significance of their native language and feel a sense of national pride.