The Korean alphabet, known as Hangul^[1] in South Korea or Chosŏn'gŭl in North Korea, has been used to write the Korean language since its creation in the 15th century by King Sejong the Great.^[4][5]

It is the official writing system of Korea, both South and North. It is a co-official writing system in the Yanbian Korean Autonomous Prefecture and Changbai Korean Autonomous County in Jilin Province, China. It is also sometimes used to write the Cia-Cia language spoken near the town of Baubau, Indonesia. The Taiwanese linguists Xu Caode (1987) developed and used a modified Hangul alphabets to represent the spoken Taiwanese, and was later supported by Ang Ui-jin (see Taiwanese Hangul).^[6][7]

The Hangul alphabet originally consisted of 28 letters with 17 consonant letters and 11 vowel letters when it was created. As four became obsolete, the modern Hangul consists of total 24 letters with 14 consonant letters and 10 vowel letters. In North Korea the total is counted 40. It consists of 19 consonant letters and 21 vowel letters as it additionally includes 5 tense consonants (ㄲ ㄸ ㅃ ㅉ ㅆ) and 20 compound and complex vowel letters as well as ㅐ.

The Korean letters are written in syllabic blocks with the alphabetic letters arranged in two dimensions. For example, the Korean word for "honeybee" (kkulbeol) is written 꿀벌, not ㄲㅜㄹㅂㅓㄹ.^[8] As it combines the features of alphabetic and syllabic writing systems, it has been described as an "alphabetic syllabary" by some linguists.^[9][10] As in traditional Chinese writing, Korean texts were traditionally written top to bottom, right to left, and are occasionally still written this way for stylistic purposes. Today, it is typically written from left to right with spaces between words and western-style punctuation.^[11]

Some linguists consider it among the most phonologically faithful writing systems in use today. One feature of Hangul is that the shapes of its consonants seemingly mimic the shapes of the speaker's mouth when pronouncing each consonant.^[9][11][12]

The Korean alphabet was originally called Hunminjeong'eum (훈민정음), after the document that introduced the script to the Korean people in 1446.^[14]

The Korean alphabet is called hangeul (한글), a name coined by Korean linguist Ju Si-gyeong in 1912. The name combines the ancient Korean word han (한), meaning "great", and geul (글), meaning "script". The word han is used to refer to Korea in general, so the name also means "Korean script".^[15] It has been romanized in multiple ways:

In North Korea it is called Chosŏn'gŭl (조선글) after Chosŏn, the North Korean name for Korea after the old name of Korea.^[16] The McCune–Reischauer system is used there.

Until the mid-20th century, the Korean elite preferred to write using Chinese characters called Hanja. They referred to Hanja as jinseo (진서/真書) or "true letters". Some accounts say the elite referred to the Korean alphabet derisively as 'amkeul (암클) meaning "women's script", and ***'*ahaetgeul (아햇글) meaning "children's script", though there is no written evidence of this.^[17]

Supporters of the Korean alphabet referred to it as jeong'eum (정음/正音) meaning "correct pronunciation", gukmun (국문/國文) meaning "national script", and eonmun (언문) meaning "vernacular script".^[17]

Before the creation of the new Korean alphabet, Koreans primarily wrote using Classical Chinese alongside native phonetic writing systems that predate the modern Korean alphabet by hundreds of years, including Idu script, Hyangchal, Gugyeol and Gakpil.^{[18][19][20][21]} However, due to fundamental differences between the Korean and Chinese languages, and the large number of characters, many lower class Koreans were illiterate.^[22] To promote literacy among the common people, the fourth king of the Joseon dynasty, Sejong the Great, personally created and promulgated a new alphabet.^[5][22][23]

The Korean alphabet was designed so that people with little education could learn to read and write. A popular saying about the alphabet is, "A wise man can acquaint himself with them before the morning is over; even a stupid man can learn them in the space of ten days."^[24]

The project was completed in late December 1443 or January 1444, and described in 1446 in a document titled Hunminjeong'eum (The Proper Sounds for the Education of the People), after which the alphabet itself was originally named.^[17] The publication date of the Hunminjeongeum, October 9, became Hangul Day in South Korea. Its North Korean equivalent, Chosŏn'gŭl Day, is on January 15.

Another document published in 1446 and titled Hunminjeong'eum Haerye ("Hunminjeong'eum Explanation and Examples") was discovered in 1940. This document explains that the design of the consonant letters is based on articulatory phonetics and the design of the vowel letters are based on the principles of yin and yang and vowel harmony.

The Korean alphabet faced opposition in the 1440s by the literary elite, including politician Choe Manri and other Korean Confucian scholars. They believed Hanja was the only legitimate writing system. They also saw the circulation of the Korean alphabet as a threat to their status.^[22] However, the Korean alphabet entered popular culture as King Sejong had intended, used especially by women and writers of popular fiction.^[25]

King Yeonsangun banned the study and publication of the Korean alphabet in 1504, after a document criticizing the king was published.^[26] Similarly, King Jungjong abolished the Ministry of Eonmun, a governmental institution related to Hangul research, in 1506.^[27]

The late 16th century, however, saw a revival of the Korean alphabet as gasa and sijo poetry flourished. In the 17th century, the Korean alphabet novels became a major genre.^[28] However, the use of the Korean alphabet had gone without orthographical standardization for so long that spelling had become quite irregular.^[25]

In 1796, the Dutch scholar Isaac Titsingh became the first person to bring a book written in Korean to the Western world. His collection of books included the Japanese book, Sangoku Tsūran Zusetsu (An Illustrated Description of Three Countries) by Hayashi Shihei.^[29] This book, which was published in 1785, described the Joseon Kingdom^[30] and the Korean alphabet.^[31] In 1832, the Oriental Translation Fund of Great Britain and Ireland supported the posthumous abridged publication of Titsingh's French translation.^[32]

Thanks to growing Korean nationalism, the Gabo Reformists' push, and Western missionaries' promotion of the Korean alphabet in schools and literature,^[33] the Hangul Korean alphabet was adopted in official documents for the first time in 1894.^[26] Elementary school texts began using the Korean alphabet in 1895, and Tongnip Sinmun, established in 1896, was the first newspaper printed in both Korean and English.^[34]

After the Japanese annexation, which occurred in 1910, Japanese was made the official language of Korea. However, the Korean alphabet was still taught in Korean-established schools built after the annexation and Korean was written in a mixed Hanja-Hangul script, where most lexical roots were written in Hanja and grammatical forms in the Korean alphabet. Japan banned earlier Korean literature from public schooling, which became mandatory for children.

The orthography of the Korean alphabet was partially standardized in 1912, when the vowel arae'a (ㆍ)–which has now disappeared from Korean–was restricted to Sino-Korean roots: the emphatic consonants were standardized to ㅺ, ㅼ, ㅽ, ㅆ, ㅾ and final consonants restricted to ㄱ, ㄴ, ㄹ, ㅁ, ㅂ, ㅅ, ㅇ, ㄺ, ㄻ, ㄼ. Long vowels were marked by a diacritic dot to the left of the syllable, but this was dropped in 1921.^[25]

A second colonial reform occurred in 1930. The arae-a was abolished: the emphatic consonants were changed to ㄲ, ㄸ, ㅃ, ㅆ, ㅉ and more final consonants ㄷ, ㅈ, ㅌ, ㅊ, ㅍ, ㄲ, ㄳ, ㄵ, ㄾ, ㄿ, ㅄ were allowed, making the orthography more morphophonemic. The double-consonant ㅆ was written alone (without a vowel) when it occurred between nouns, and the nominative particle -가 was introduced after vowels, replacing -이.^[25]

Ju Si-gyeong, the linguist who had coined the term Hangul to replace Eonmun or "Vulgar Script" in 1912, established the Korean Language Research Society (later renamed the Hangul Society), which further reformed orthography with Standardized System of Hangul in 1933. The principal change was to make the Korean alphabet as morphophonemically practical given the existing letters.^[25] A system for transliterating foreign orthographies was published in 1940.

However, Japan banned the Korean language from schools in 1938 as part of a policy of cultural assimilation,^[35] and all Korean-language publications were outlawed in 1941.^[36]

The definitive modern Korean alphabet orthography was published in 1946, just after Korean independence from Japanese rule. In 1948, North Korea attempted to make the script perfectly morphophonemic through the addition of new letters, and in 1953, Syngman Rhee in South Korea attempted to simplify the orthography by returning to the colonial orthography of 1921, but both reforms were abandoned after only a few years.^[25]

Both North Korea and South Korea have used the Korean alphabet or mixed script as their official writing system, with ever-decreasing use of Hanja. Beginning in the 1970s, Hanja began to experience a gradual decline in commercial or unofficial writing in the South due to government intervention, with some South Korean newspapers now only using Hanja as abbreviations or disambiguation of homonyms. There has been widespread debate as to the future of Hanja in South Korea. North Korea instated the Korean alphabet as its exclusive writing system in 1949, and banned the use of Hanja completely.

While both North Korea and South Korea claim 99 percent literacy, a 2003 study found that 25 percent of those in the older generation in the South were not completely literate in the Korean alphabet.^[37]

The Hunminjeong'eum Society in Seoul attempts to spread the use of the Korean alphabet to unwritten languages of Asia.^[38] In 2009, the Korean alphabet was unofficially adopted by the town of Baubau, in Southeast Sulawesi, Indonesia, to write the Cia-Cia language.^[39][40][41] A number of Indonesian Cia-Cia speakers who visited Seoul generated large media attention in South Korea, and they were greeted on their arrival by Oh Se-hoon, the mayor of Seoul.^[42] It was confirmed in October 2012 that the attempts to disseminate the use of the Korean alphabet in Indonesia failed.^[43] Some people continue to use the Korean alphabet at home or co-officially.

Letters in the Korean alphabet are called jamo (자모). There are 19 consonants and 21 vowels used in the modern alphabet. They were first named in Hunmongjahoe, a hanja textbook written by Choe Sejin.

The chart below shows all 19 consonants in South Korean alphabetic order with Revised Romanization equivalents for each letter and pronunciation in IPA (see Korean phonology for more).

ㅇ is silent syllable-initially and is used as a placeholder when the syllable starts with a vowel. ㄸ, ㅃ, and ㅉ are never used syllable-finally.

Consonants in the Korean alphabet can be combined into 11 consonant clusters, which always appear in the final position in a syllable. They are: ㄳ, ㄵ, ㄶ, ㄺ, ㄻ, ㄼ, ㄽ, ㄾ, ㄿ, ㅀ, and ㅄ.

The chart below shows the 21 vowels used in the modern Korean alphabet in South Korean alphabetic order with Revised Romanization equivalents for each letter and pronunciation in IPA (see Korean phonology for more).

Alphabetic order in the Korean alphabet is called the ganada order, (가나다 순) after the first three letters of the alphabet. The alphabetical order of the Korean alphabet does not mix consonants and vowels. Rather, first are velar consonants, then coronals, labials, sibilants, etc. The vowels come after the consonants.

The order from the Hunminjeong'eum in 1446 was:

In 1527, Choe Sejin reorganized the alphabet in Hunmongjahoe:

This is the basis of the modern alphabetic orders. It was before the development of the Korean tense consonants and the double letters that represent them, and before the conflation of the letters ㅇ (') and ㆁ (ng). Thus, when the North Korean and South Korean governments implemented full use of the Korean alphabet, they ordered these letters differently, with North Korea, placing new letters at the end of the alphabet and South Korea grouping similar letters together.

The new, double, letters are placed at the end of the consonants, just before the ' ㅇ, so as not to alter the traditional order of the rest of the alphabet.

All digraphs and trigraphs, including the old diphthongs ㅐ and ㅔ, are placed after the simple vowels, again maintaining Choe's alphabetic order.

The order of the final letters is:

Unlike when it is initial, this ㅇ is pronounced, as the nasal ㅇ ng, which occurs only as a final in the modern language. The double letters are placed to the very end, as in the initial order, but the combined consonants are ordered immediately after their first element.

In the Southern order, double letters are placed immediately after their single counterparts:

The modern monophthongal vowels come first, with the derived forms interspersed according to their form: i is added first, then iotized, then iotized with added i. Diphthongs beginning with w are ordered according to their spelling, as ㅗ or ㅜ plus a second vowel, not as separate digraphs.

The order of the final letters (받침) is:

("None" means there is no final letter.)

Every syllable begins with a consonant (or the silent ㅇ) that is followed by a vowel (e.g. ㄷ + ㅏ = 다). Some syllables such as "달" and "닭" have a final consonant or final consonant cluster (받침). Then, 399 combinations are possible for "two-letter syllables" and 10,773 possible combinations for syllables with more than two "letters" (27 possible final endings), for a total of 11,172 possible combinations of Korean alphabet "letters" to form syllables.

Letters in the Korean alphabet were named by Korean linguist Choe Sejin in 1527. South Korea uses Choe's traditional names, most of which follow the format of letter + i + eu + letter. Choe described these names by listing Hanja characters with similar pronunciations. However, as the syllables 윽 euk, 읃 eut, and 읏 eut did not occur in Hanja, Choe gave those letters the modified names 기역 giyeok, 디귿 digeut, and 시옷 siot, using Hanja that didn't fit the pattern (for 기역) or native Korean syllables (for 디귿 and 시옷).

Originally, Choe gave ㅈ, ㅊ, ㅋ, ㅌ, ㅍ, and ㅎ the irregular one-syllable names of ji, chi, ḳi, ṭi, p̣i, and hi, because they should not be used as final consonants, as specified in Hunminjeong'eum. However, after establishment of the new orthography in 1933, which let all consonants be used as finals, the names changed to the present forms.

North Korea regularized Choe's original names when it made the Korean alphabet its official orthography.

The chart below shows names used in North Korea for consonants in the Korean alphabet. The letters are arranged in North Korean alphabetic order, and the letter names are romanised with the McCune-Reischauer system, which is widely used in North Korea. The tense consonants are described with the word 된 toen meaning "hard".

In North Korea, an alternative way to refer to a consonant is letter + ŭ (ㅡ), for example, gŭ (그) for the letter ㄱ, and ssŭ (쓰) for the letter ㅆ.

As in South Korea, the names of vowels in the Korean alphabet are the same as the sound of each vowel.

The chart below shows names used in South Korea for consonants of the Korean alphabet. The letters are arranged in the South Korean alphabetic order, and the letter names are romanised in the Revised Romanization system, which is the official romanization system of South Korea. The tense consonants are described with the word 쌍 ssang meaning "double".

Letters in the Korean alphabet have adopted certain rules of Chinese calligraphy, although ㅇ and ㅎ use a circle, which is not used in printed Chinese characters.

For the iotized vowels, which are not shown, the short stroke is simply doubled.

Scripts typically transcribe languages at the level of morphemes (logographic scripts like Hanja), of syllables (syllabaries like kana), of segments (alphabetic scripts like the Latin script used to write English and many other languages), or, on occasion, of distinctive features. The Korean alphabet incorporates aspects of the latter three, grouping sounds into syllables, using distinct symbols for segments, and in some cases using distinct strokes to indicate distinctive features such as place of articulation (labial, coronal, velar, or glottal) and manner of articulation (plosive, nasal, sibilant, aspiration) for consonants, and iotization (a preceding *i-*sound), harmonic class and i-mutation for vowels.

For instance, the consonant ㅌ ṭ [tʰ] is composed of three strokes, each one meaningful: the top stroke indicates ㅌ is a plosive, like ㆆ ʔ, ㄱ g, ㄷ d, ㅈ j, which have the same stroke (the last is an affricate, a plosive–fricative sequence); the middle stroke indicates that ㅌ is aspirated, like ㅎ h, ㅋ ḳ, ㅊ ch, which also have this stroke; and the bottom stroke indicates that ㅌ is alveolar, like ㄴ n, ㄷ d, and ㄹ l. (This element is said to represent the shape of the tongue when pronouncing coronal consonants, though this is not certain.) Two consonants, ㆁ and ㅱ, have dual pronunciations, and appear to be composed of two elements corresponding to these two pronunciations: [ŋ]~silence for ㆁ and [m]~[w] for obsolete ㅱ.

With vowel letters, a short stroke connected to the main line of the letter indicates that this is one of the vowels that can be iotized; this stroke is then doubled when the vowel is iotized. The position of the stroke indicates which harmonic class the vowel belongs to, "light" (top or right) or "dark" (bottom or left). In the modern alphabet, an additional vertical stroke indicates i-mutation, deriving ㅐ [ɛ], ㅚ [ø], and ㅟ [y] from ㅏ [a], ㅗ [o], and ㅜ [u]. However, this is not part of the intentional design of the script, but rather a natural development from what were originally diphthongs ending in the vowel ㅣ [i]. Indeed, in many Korean dialects, including the standard dialect of Seoul, some of these may still be diphthongs. Note: ㅔ [e] as a morpheme is ㅓ combined with ㅣ as a vertical stroke. As a phoneme, its sound is not by i-mutation of ㅓ [ʌ].

Some linguists have praised the Korean alphabet for its featural design; beyond the fact that the shapes of the letters are related to the features of the sounds they represent, the Korean alphabet also attracts approval for the fact that vowels are made from vertical or horizontal lines so that they are easily distinguishable from consonants.

Although the design of the script may be featural, for all practical purposes it behaves as an alphabet. The letter ㅌ is not read as three letters alveolar aspirated plosive, for instance, but as a single consonant t. Likewise, the former diphthong ㅔ is read as a single vowel e.

Beside the letters, the Korean alphabet originally employed diacritic marks to indicate pitch accent. A syllable with a high pitch (거성) was marked with a dot (ᅟᅠ〮) to the left of it (when writing vertically); a syllable with a rising pitch (상성) was marked with a double dot, like a colon (ᅟᅠ〯). These are no longer used, as modern Seoul Korean has lost tonality. Vowel length has also been neutralized in Modern Korean,^[44] and is no longer written.

The consonant letters fall into five homorganic groups, each with a basic shape, and one or more letters derived from this shape by means of additional strokes. In the Hunmin Jeong-eum Haerye account, the basic shapes iconically represent the articulations the tongue, palate, teeth, and throat take when making these sounds.

The Korean names for the groups are taken from Chinese phonetics:

Vowel letters are based on three elements:

Short strokes (dots in the earliest documents) were added to these three basic elements to derive the vowel letter:

The Korean alphabet does not have a letter for w sound. Since an o or u before an a or eo became a [w] sound, and [w] occurred nowhere else, [w] could always be analyzed as a phonemic o or u, and no letter for [w] was needed. However, vowel harmony is observed: "dark" ㅜ u with "dark" ㅓ eo for ㅝ wo; "bright" ㅗ o with "bright" ㅏ a for ㅘ wa:

The compound vowels ending in ㅣ i were originally diphthongs. However, several have since evolved into pure vowels:

There is no letter for y. Instead, this sound is indicated by doubling the stroke attached to the baseline of the vowel letter. Of the seven basic vowels, four could be preceded by a y sound, and these four were written as a dot next to a line. (Through the influence of Chinese calligraphy, the dots soon became connected to the line: ㅓㅏㅜㅗ.) A preceding y sound, called "iotization", was indicated by doubling this dot: ㅕㅑㅠㅛ yeo, ya, yu, yo. The three vowels that could not be iotized were written with a single stroke: ㅡㆍㅣ eu, (arae a), i.

The simple iotized vowels are:

There are also two iotized diphthongs:

The Korean language of the 15th century had vowel harmony to a greater extent than it does today. Vowels in grammatical morphemes changed according to their environment, falling into groups that "harmonized" with each other. This affected the morphology of the language, and Korean phonology described it in terms of yin and yang: If a root word had yang ('bright') vowels, then most suffixes attached to it also had to have yang vowels; conversely, if the root had yin ('dark') vowels, the suffixes had to be yin as well. There was a third harmonic group called "mediating" ('neutral' in Western terminology) that could coexist with either yin or yang vowels.

The Korean neutral vowel was ㅣ i. The yin vowels were ㅡㅜㅓ eu, u, eo; the dots are in the yin directions of 'down' and 'left'. The yang vowels were ㆍㅗㅏ ə, o, a, with the dots in the yang directions of 'up' and 'right'. The Hunmin Jeong-eum Haerye states that the shapes of the non-dotted letters ㅡㆍㅣ were chosen to represent the concepts of yin, yang, and mediation: Earth, Heaven, and Human. (The letter ㆍ ə is now obsolete except in the Jeju language.)

The third parameter in designing the vowel letters was choosing ㅡ as the graphic base of ㅜ and ㅗ, and ㅣ as the graphic base of ㅓ and ㅏ. A full understanding of what these horizontal and vertical groups had in common would require knowing the exact sound values these vowels had in the 15th century.

The uncertainty is primarily with the three letters ㆍㅓㅏ. Some linguists reconstruct these as *a, *ɤ, *e, respectively; others as *ə, *e, *a. A third reconstruction is to make them all middle vowels as *ʌ, *ɤ, *a.^[45] With the third reconstruction, Middle Korean vowels actually line up in a vowel harmony pattern, albeit with only one front vowel and four middle vowels:

However, the horizontal letters ㅡㅜㅗ eu, u, o do all appear to have been mid to high back vowels, [*ɯ, *u, *o], and thus to have formed a coherent group phonetically in every reconstruction.

The traditionally accepted account^[2][46] on the design of the letters is that the vowels are derived from various combinations of the following three components: ㆍ ㅡ ㅣ. Here, ㆍ symbolically stands for the (sun in) heaven, ㅡ stands for the (flat) earth, and ㅣ stands for an (upright) human. The original sequence of the Korean vowels, as stated in Hunminjeongeum, listed these three vowels first, followed by various combinations. Thus, the original order of the vowels was: ㆍ ㅡ ㅣ ㅗ ㅏ ㅜ ㅓ ㅛ ㅑ ㅠ ㅕ. Note that two positive vowels (ㅗ ㅏ) including one ㆍ are followed by two negative vowels including one ㆍ, then by two positive vowels each including two of ㆍ, and then by two negative vowels each including two of ㆍ.

The same theory provides the most simple explanation of the shapes of the consonants as an approximation of the shapes of the most representative organ needed to form that sound. The original order of the consonants in Hunminjeong'eum was: ㄱ ㅋ ㆁ ㄷ ㅌ ㄴ ㅂ ㅍ ㅁ ㅈ ㅊ ㅅ ㆆ ㅎ ㅇ ㄹ ㅿ.

ㄱ representing the /k/ sound geometrically describes a tongue just before the moment of pronunciation as the tongue blocks the passage of air.

ㅋ representing the /kʰ/ sound is derived from ㄱ by adding another stroke.

ㆁ representing the /ŋ/ sound may have been derived from ㅇ by addition of a stroke.

ㄷ representing the /t/ sound is derived from ㄴ by addition of a stroke.

ㅌ representing the /tʰ/ sound is derived from ㄷ by adding another stroke.

ㄴ representing the /n/ sound geometrically describes a tongue making contact with an upper palate just before making the "n" sound.

ㅂ representing the /p/ sound is derived from ㅁ by adding strokes.

ㅍ representing the /pʰ/ sound is a variant of ㅂ, which is obtained by rotating 90 degrees and extending the horizontal strokes.

ㅁ representing the /m/ sound geometrically describes a closed mouth before opening the lips.

ㅈ representing the /tɕ/ sound is derived from the shape of ㅅ by adding strokes.

ㅊ representing the /tɕʰ/ sound is derived from ㅈ by adding another stroke.

ㅅ representing the /s/ sound geometrically describes a near contact between the tongue and the teeth.

ㆆ representing the /ʔ/ sound geometrically describes an open throat with a bar to indicate that there is an aspiration.

ㅎ representing the /h/ sound is derived from ㆆ with the extra stroke representing a stronger flow of the aspiration.

ㅇ representing the absence of a consonant geometrically describes an open mouth, which necessarily accompanies the following vowel.

ㄹ representing the /ɾ/ and /l/ sounds geometrically describes a backward-bending tongue.

ㅿ representing a weak /z/ sound is also derived from the shape of the teeth, but has a different origin than ㅅ and is not derived from ㅅ by addition of a stroke.

Although the Hunminjeong'eum Haerye explains the design of the consonantal letters in terms of articulatory phonetics, as a purely innovative creation, several theories suggest which external sources may have inspired or influenced King Sejong's creation. Professor Gari Ledyard of Columbia University studied possible connections between Hangul and the Mongol 'Phags-pa script of the Yuan dynasty. He believed that the role of 'Phags-pa script in the creation of the Korean alphabet was quite limited:

Ledyard posits that five of the Korean letters have shapes inspired by 'Phags-pa; a sixth basic letter, the null initial ㅇ, was invented by Sejong. The rest of the letters were derived internally from these six, essentially as described in the Hunmin Jeong-eum Haerye. However, the five borrowed consonants were not the graphically simplest letters considered basic by the Hunmin Jeong-eum Haerye, but instead the consonants basic to Chinese phonology: ㄱ, ㄷ, ㅂ, ㅈ, and ㄹ.

The Hunmin Jeong-eum states that King Sejong adapted the 古篆 (gojeon, "Gǔ Seal Script") in creating the Korean alphabet. The 古篆 has never been identified. The primary meaning of 古 gǔ is "old" ("Old Seal Script"), frustrating philologists because the Korean alphabet bears no functional similarity to Chinese 篆字 zhuànzì seal scripts. However, Ledyard believes 古 gǔ may be a pun on 蒙古 Měnggǔ "Mongol", and that 古篆 is an abbreviation of 蒙古篆字 "Mongol Seal Script", that is, the formal variant of the 'Phags-pa alphabet written to look like the Chinese seal script. There were 'Phags-pa manuscripts in the Korean palace library, including some in the seal-script form, and several of Sejong's ministers knew the script well.

If this was the case, Sejong's evasion on the Mongol connection can be understood in light of Korea's relationship with Ming China after the fall of the Mongol Yuan dynasty, and of the literati's contempt for the Mongols as "barbarians".

According to Ledyard, the five borrowed letters were graphically simplified, which allowed for consonant clusters and left room to add a stroke to derive the aspirate plosives, ㅋㅌㅍㅊ. But in contrast to the traditional account, the non-plosives (ㆁ ㄴ ㅁ ㅅ) were derived by removing the top of the basic letters. He points out that while it is easy to derive ㅁ from ㅂ by removing the top, it is not clear how to derive ㅂ from ㅁ in the traditional account, since the shape of ㅂ is not analogous to those of the other plosives.

The explanation of the letter ng also differs from the traditional account. Many Chinese words began with ng, but by King Sejong's day, initial ng was either silent or pronounced [ŋ] in China, and was silent when these words were borrowed into Korean. Also, the expected shape of ng (the short vertical line left by removing the top stroke of ㄱ) would have looked almost identical to the vowel ㅣ [i]. Sejong's solution solved both problems: The vertical stroke left from ㄱ was added to the null symbol ㅇ to create ㆁ (a circle with a vertical line on top), iconically capturing both the pronunciation [ŋ] in the middle or end of a word, and the usual silence at the beginning. (The graphic distinction between null ㅇ and ng ㆁ was eventually lost.)

Another letter composed of two elements to represent two regional pronunciations was ㅱ, which transcribed the Chinese initial 微. This represented either m or w in various Chinese dialects, and was composed of ㅁ [m] plus ㅇ (from 'Phags-pa [w]). In 'Phags-pa, a loop under a letter represented w after vowels, and Ledyard hypothesized that this became the loop at the bottom of ㅱ. In 'Phags-pa the Chinese initial 微 is also transcribed as a compound with w, but in its case the w is placed under an h. Actually, the Chinese consonant series 微非敷 w, v, f is transcribed in 'Phags-pa by the addition of a w under three graphic variants of the letter for h, and the Korean alphabet parallels this convention by adding the w loop to the labial series ㅁㅂㅍ m, b, p, producing now-obsolete ㅱㅸㆄ w, v, f. (Phonetic values in Korean are uncertain, as these consonants were only used to transcribe Chinese.)

As a final piece of evidence, Ledyard notes that most of the borrowed Korean letters were simple geometric shapes, at least originally, but that ㄷ d [t] always had a small lip protruding from the upper left corner, just as the 'Phags-pa ꡊ d [t] did. This lip can be traced back to the Tibetan letter ད d.

Numerous obsolete Korean letters and sequences are no longer used in Korean. Some of these letters were only ever used to represent the sounds of Chinese rime tables. Some of the Korean sounds represented by these obsolete letters still exist in some dialects.

In the original Korean alphabet system, double letters were used to represent Chinese voiced (濁音) consonants, which survive in the Shanghainese slack consonants and were not used for Korean words. It was only later that a similar convention was used to represent the modern "tense" (faucalized) consonants of Korean.

The sibilant ("dental") consonants were modified to represent the two series of Chinese sibilants, alveolar and retroflex, a "round" vs. "sharp" distinction (analogous to s vs sh) which was never made in Korean, and was even being lost from southern Chinese. The alveolar letters had longer left stems, while retroflexes had longer right stems:

To make the Korean alphabet a better morphophonological fit to the Korean language, North Korea introduced six new letters, which were published in the New Orthography for the Korean Language and used officially from 1948 to 1954.

Two obsolete letters were restored: ⟨ㅿ⟩ (리읃), which was used to indicate an alternation in pronunciation between initial /l/ and final /d/; and ⟨ㆆ⟩ (히으), which was only pronounced between vowels. Two modifications of the letter ㄹ were introduced, one for a ㄹ, which is silent finally, and one for a ㄹ, which doubled between vowels. A hybrid ㅂ-ㅜ letter was introduced for words that alternated between those two sounds (that is, a /b/, which became /w/ before a vowel). Finally, a vowel ⟨1⟩ was introduced for variable iotation.

Hangul Jamo (U+1100–U+11FF) and Hangul Compatibility Jamo (U+3130–U+318F) blocks were added to the Unicode Standard in June 1993 with the release of version 1.1. The characters were relocated to their present locations in July, 1996 with the release of version 2.0.

Hangul Jamo Extended-A (U+A960–U+A97F) and Hangul Jamo Extended-B (U+D7B0–U+D7FF) blocks were added to the Unicode Standard in October 2009 with the release of version 5.2.

Parenthesised (U+3200–U+321E) and circled (U+3260–U+327E) Hangul compatibility characters are in the Enclosed CJK Letters and Months block:

Half-width Hangul compatibility characters (U+FFA0–U+FFDC) are in the Halfwidth and Fullwidth Forms block:

The Korean alphabet in other Unicode blocks:

Except for a few grammatical morphemes prior to the twentieth century, no letter stands alone to represent elements of the Korean language. Instead, letters are grouped into syllabic or morphemic blocks of at least two and often three: a consonant or a doubled consonant called the initial (초성, 初聲 choseong syllable onset), a vowel or diphthong called the medial (중성, 中聲 jungseong syllable nucleus), and, optionally, a consonant or consonant cluster at the end of the syllable, called the final (종성, 終聲 jongseong syllable coda). When a syllable has no actual initial consonant, the null initial ㅇ ieung is used as a placeholder. (In the modern Korean alphabet, placeholders are not used for the final position.) Thus, a block contains a minimum of two letters, an initial and a medial. Although the Korean alphabet had historically been organized into syllables, in the modern orthography it is first organized into morphemes, and only secondarily into syllables within those morphemes, with the exception that single-consonant morphemes may not be written alone.

The sets of initial and final consonants are not the same. For instance, ㅇ ng only occurs in final position, while the doubled letters that can occur in final position are limited to ㅆ ss and ㄲ kk.

Not including obsolete letters, 11,172 blocks are possible in the Korean alphabet.

The placement or "stacking" of letters in the block follows set patterns based on the shape of the medial.

Consonant and vowel sequences such as ㅄ bs, ㅝ wo, or obsolete ㅵ bsd, ㆋ üye are written left to right.

Vowels (medials) are written under the initial consonant, to the right, or wrap around the initial from bottom to right, depending on their shape: If the vowel has a horizontal axis like ㅡ eu, then it is written under the initial; if it has a vertical axis like ㅣ i, then it is written to the right of the initial; and if it combines both orientations, like ㅢ ui, then it wraps around the initial from the bottom to the right:

A final consonant, if present, is always written at the bottom, under the vowel. This is called 받침 batchim "supporting floor":

A complex final is written left to right:

Blocks are always written in phonetic order, initial-medial-final. Therefore:

Normally the resulting block is written within a square of the same size and shape as a Hanja (Chinese character) by compressing or stretching the letters to fill the bounds of the block, so someone not familiar with the scripts may mistake the Korean alphabet for Hanja or Chinese.

However, some recent fonts (for example Eun,^[52] HY깊은샘물M, UnJamo) move towards the European practice of letters whose relative size is fixed, and use whitespace to fill letter positions not used in a particular block, and away from the East Asian tradition of square block characters (方块字). They break one or more of the traditional rules:

These fonts have been used as design accents on signs or headings, rather than for typesetting large volumes of body text.

There was a minor and unsuccessful movement in the early twentieth century to abolish syllabic blocks and write the letters individually and in a row, in the fashion of writing Latin alphabet as in English and other European languages, instead of the standard convention of 모아쓰기 (moa-sseugi 'assembled writing'). For example, ㅎㅏㄴㄱㅡㄹ would be written for 한글 (Hangeul).^[53] It is called 풀어쓰기 (pureo-sseugi 'unassembled writing').

Avant-garde typographer Ahn Sangsu made a font for the "Hangul Dada" exposition that exploded the syllable blocks; but while it strings out the letters horizontally, it retains the distinctive vertical position each letter would normally have within a block, unlike the older linear writing proposals.^[54]

Until the 20th century, no official orthography of the Korean alphabet had been established. Due to liaison, heavy consonant assimilation, dialectal variants and other reasons, a Korean word can potentially be spelled in multiple ways. Sejong seemed to prefer morphophonemic spelling (representing the underlying root forms) rather than a phonemic one (representing the actual sounds). However, early in its history the Korean alphabet was dominated by phonemic spelling. Over the centuries the orthography became partially morphophonemic, first in nouns and later in verbs. The modern Korean alphabet is as morphophonemic as is practical. The difference between phonetic Romanization, phonemic orthography and morpho-phonemic orthography can be illustrated with the phrase motaneun sarami:

After the Gabo Reform in 1894, the Joseon Dynasty and later the Korean Empire started to write all official documents in the Korean alphabet. Under the government's management, proper usage of the Korean alphabet and Hanja, including orthography, was discussed, until the Korean Empire was annexed by Japan in 1910.

The Government-General of Korea popularised a writing style that mixed Hanja and the Korean alphabet, and was used in the later Joseon dynasty. The government revised the spelling rules in 1912, 1921 and 1930, to be relatively phonemic.

The Hangul Society, founded by Ju Si-gyeong, announced a proposal for a new, strongly morphophonemic orthography in 1933, which became the prototype of the contemporary orthographies in both North and South Korea. After Korea was divided, the North and South revised orthographies separately. The guiding text for orthography of the Korean alphabet is called Hangeul Matchumbeop, whose last South Korean revision was published in 1988 by the Ministry of Education.

Since the Late Joseon dynasty period, various Hanja-Hangul mixed systems were used. In these systems, Hanja were used for lexical roots, and the Korean alphabet for grammatical words and inflections, much as kanji and kana are used in Japanese. Hanja have been almost entirely phased out of daily use in North Korea, and in South Korea they are mostly restricted to parenthetical glosses for proper names and for disambiguating homonyms.

Indo-Arabic numerals are mixed in with the Korean alphabet, e.g. 2007년 3월 22일 (22 March 2007).

Latin script and occasionally other scripts may be sprinkled within Korean texts for illustrative purposes, or for unassimilated loanwords. Very occasionally non-Hangul letters may be mixed into Korean syllabic blocks, as Gㅏ Ga at right.

Because of syllable clustering, words are shorter on the page than their linear counterparts would be, and the boundaries between syllables are easily visible (which may aid reading, if segmenting words into syllables is more natural for the reader than dividing them into phonemes).^[55] Because the component parts of the syllable are relatively simple phonemic characters, the number of strokes per character on average is lower than in Chinese characters. Unlike syllabaries, such as Japanese kana, or Chinese logographs, none of which encode the constituent phonemes within a syllable, the graphic complexity of Korean syllabic blocks varies in direct proportion with the phonemic complexity of the syllable.^[56] Unlike linear alphabets such as those derived from Latin, Korean orthography allows the reader to "utilize both the horizontal and vertical visual fields".^[57] Finally, since Korean syllables are represented both as collections of phonemes and as unique-looking graphs, they may allow for both visual and aural retrieval of words from the lexicon.

The Korean alphabet may be written either vertically or horizontally. The traditional direction is from top to bottom, right to left. Horizontal writing in the style of the Latin script was promoted by Ju Si-gyeong, and has become overwhelmingly prevalent.

In Hunmin Jeongeum, the Korean alphabet was printed in sans-serif angular lines of even thickness. This style is found in books published before about 1900, and can be found in stone carvings (on statues, for example).

Over the centuries, an ink-brush style of calligraphy developed, employing the same style of lines and angles as traditional Korean calligraphy. This brush style is called gungche (궁체 宮體), which means "Palace Style" because the style was mostly developed and used by the maidservants (gungnyeo, 궁녀 宮女) of the court in Joseon dynasty.

Modern styles that are more suited for printed media were developed in the 20th century. In 1993, new names for both Myeongjo (明朝) and Gothic styles were introduced when Ministry of Culture initiated an effort to standardize typographic terms, and the names Batang (바탕, meaning "background") and Dotum (돋움, meaning "stand out") replaced Myeongjo and Gothic respectively. These names are also used in Microsoft Windows.

A sans-serif style with lines of equal width is popular with pencil and pen writing and is often the default typeface of Web browsers. A minor advantage of this style is that it makes it easier to distinguish -eung from -ung even in small or untidy print, as the jongseong ieung (ㅇ) of such fonts usually lacks a serif that could be mistaken for the short vertical line of the letter ㅜ (u).