The Korean alphabet, known in South Korea as Hangul (also transcribed Hangeul) and as Chosŏn'gŭl/Chosŏn Muntcha in North Korea and China, is the alphabet that has been used to write the Korean language since the 15th century. It was created during the Joseon Dynasty in 1443 by King Sejong the Great. Now, the alphabet is the official script of both South Korea and North Korea, and co-official in the Yanbian Korean Autonomous Prefectureand Changbai Korean Autonomous County of China's Jilin Province. In South Korea, Hangul is used primarily to write the Korean language as using Hanja (Chinese characters) in typical Korean writing had fallen out of common usage during the late 1990s. Hanja is still used to some extent in art, academic and government documents, newspapers, and high level Korean in South Korea; however, North Korea banned the use of Hanja in public since 1964.
In its classical and modern forms, the alphabet has 19 consonant and 21 vowel letters. However, instead of being written sequentially like the letters of the Latin alphabet, Hangul letters are grouped into blocks, such as 한 han, each of which transcribes a syllable. That is, although the syllable 한 han may look like a single character, it is actually composed of three letters: ㅎ h, ㅏ a, and ㄴ n. Each syllabic block consists of two to six letters, including at least one consonant and one vowel. These blocks are then arranged horizontally from left to right or vertically from top to bottom. Each Korean word consists of one or more syllables, hence one or more blocks. The number of mathematically possible distinct blocks is 11,172 (see "South Korean order" below), though there are far fewer possible syllables allowed by Korean phonotactics, and not all phonotactically possible syllables occur in actual Korean words. For a phonological description, see Korean phonology. Among possible 11,172 Hangul syllables the most frequent 256 have cumulative frequency of 88.2% and with the top 512 ones it reaches 99.9%.