quality:corruption
Hangul

King Sejong profoundly affected Korea's history with the creation and introduction of hangul, the native phonetic writing system for the Korean language. Although it is widely assumed that he ordered the Hall of Worthies to invent the script, contemporaneous records such as the Veritable Records of King Sejong and Jeong In-ji 's preface to the Hunminjeongeum Haerye emphasize that Sejong invented it himself.

Before the creation of the new alphabet, the people of Joseon primarily used Classical Chinese to write, alongside a few writing systems like idu, hyangchal, gugyeol, and gakpil —which used Chinese characters to approximate sounds of the Korean language—that had been in use since hundreds of years before hangul. However, due to the fundamental differences between the Korean and Chinese languages, and the large number of Chinese characters required, lower-class people of Joseon lacked the privilege of education and were illiterate. To promote literacy, King Sejong created hangul (which initially had 28 letters, four of which are no longer in use).

Hangul was completed in 1443 and published in 1446 along with a 33-page manual titled Hunminjeongeum, explaining what the letters are as well as the philosophical theories and motives behind them.

King Sejong faced backlash from the noble class as many disapproved of the idea of a common writing system, with some openly opposing its creation. Many within the nobility believed that giving the peasants the ability to read and write would allow them to find and abuse loopholes within the law. Others felt that hangul would threaten their families’ positions in court by creating a larger pool of civil servants. The Joseon elite continued to use the Chinese hanja long after Sejong’s death. Hangul was often treated with contempt by those in power and received criticism in the form of nicknames, including eonmun ("vulgar script"), amkeul ("women’s script"), and ahaekkeul ("children’s script"). It was commonly used for areas like casual writing, prose and bookkeeping, especially by the urban middle class like administrators and bureaucrats. It notably gained popularity among women and fiction writers, with former usually often not having been able to get access to hanja education.

In 1504, the study and publication of hangul was banned by Yeonsangun. Its spread and preservation can be largely attributed to three main factors: books published for women, its use by Buddhist monks, and the introduction of Christianity in Korea in 1602. Hangul was brought into the mainstream culture in the 16th century, due to a renaissance in literature and poetry. It continued to gain popularity well into the 17th century, and gained wider use after a period of nationalism in the 19th century. In 1849, it was adopted as Korea’s national writing system, and saw its first use in official government documents. After the Treaty of 1910, hangul was outlawed again until the liberation of Korea in 1945.