The term Hunminjeongeum (Correct Sounds for Instructing the People) has three meanings: it was the original name of the Korean alphabet, which was renamed Hangeul (meaning "Great Letters") in the 20th century; it is the title of a book explaining its use and published when the alphabet was promulgated on the 10th day of the Ninth Moon in 1446 (October 9); and it is the title of the main chapter of the book.
The writing system was created by the fourth monarch of the Joseon Dynasty (1392-1910), King Sejong the Great (r. 1418-1450). Before its creation, Korean had been written using Chinese characters, which were awkward because the two languages had different structures and which took long years to learn, so that only the upper class could read and write. Dismayed by this situation, King Sejong, working with scholars in the Jiphyeonjeon (Hall of Worthies), personally created a phonetic alphabet suited to the Korean language. Completed in the 12th Moon of 1443, the alphabet consisted of 28 letters, 24 of which are still in use today. The alphabet is generally recognized as being both unique and scientific unique in that it is the only alphabet originally created by a single person at a specific time without being based on a previously known script and scientific because it is based on a knowledge of phonology and phonetics. In addition, it was based on the principles of Neo-Confucian philosophy.
When the alphabet was promulgated, King Sejong wrote an introduction describing the reasons for its creation. He also had the scholars of the Hall of Worthies write a general explanation and examples of its use. These were published under the title Hunminjeongeum, and, as a result, the use of the alphabet spread among the general population. Its publication was a truly momentous event in Korean history, and the document which has been preserved to this day is a valued National Treasure.