Hanja
Although a phonetic Korean alphabet, now known as Chosŏn'gŭl or Hangul, had been created by Sejong the Great, it did not come into widespread official use until the late 19th and early 20th century. Thus, until that time it was necessary to be fluent in reading and writing Hanja in order to be literate in Korean, as the vast majority of Korean literature and most other Korean documents were written in Literary Chinese, using Hanja as its primary script. Today, a good working knowledge of Chinese characters is still important for anyone who wishes to study older texts (up to about the 1990s), or anyone who wishes to read scholarly texts in the humanities. Learning a certain number of Hanja is very helpful for understanding the etymology of Sino-Korean words, and for enlarging one's Korean vocabulary. Today, Hanja are not used to write native Korean words, which are always rendered in Hangul, and even words of Chinese origin—"Hanja-eo" ()—are written with the Hangul alphabet most of the time, with the corresponding Chinese character often written next to it in order to prevent confusion with other characters or words with the same phonetics.
Adoption of Chinese literary culture
Early attempts to write the Korean language used a number of complex and unwieldy systems collectively known as Idu, using Chinese characters both for their meaning and their sound.
The Hangul alphabet announced in 1446 brought Korean reading and writing within reach of virtually the entire population.
King Sejong's announcement of the new script, "The Correct Sounds for the Instruction of the People", was itself written in Literary Chinese like most such documents, and described the new letters in terms of Chinese metaphysics.
Although the new script was clearly more efficient, it was limited to informal writing and recording of folk tales until, as part of the Gabo Reform in December 1894, the civil examinations were abolished and government documents were required to be printed in Korean.
Even then Korean was written with a composite script, with Chinese characters (Hanja) for the Sino-Korean words that now made up over half the vocabulary of the language interspersed with Hangul for native words and suffixes.
Hanja are still taught in schools in both parts of Korea, but fell out of use in North Korea in the late 1940s, and are increasingly rarely used in South Korea.