Jamo

Jamo refers to the individual letters that make up Hangul, the Korean writing system. They are divided into consonants (ja-eum) and vowels (mo-eum). In modern Korean, there are 19 consonant jamo and 21 vowel jamo, though historical inventories included additional letters that are now obsolete. Jamo can be written alone or combined to form syllable blocks.

Hangul was created in the mid-15th century during the reign of King Sejong the Great and his scholars, as described in the Hunminjeongeum. The project aimed to provide a simple, phonemically faithful script for literacy and daily use, supplementing or replacing earlier writing systems that relied on complex Chinese characters.

In use, jamo are assembled into syllable blocks that typically begin with an initial consonant, followed by a vowel nucleus, and often end with a final consonant. Vowels can be simple or compound, with many diphthongs and ligatures represented by combinations of jamo, such as ㅘ, ㅙ, and ㅚ. The shapes of the consonant jamo in particular have historical featural design, reflecting articulatory properties like where the tongue or lips are positioned.

In computing, jamo are encoded in Unicode in the Hangul Jamo blocks, with additional ranges for extended or historical letters used in academic study or transcription. Some letters are no longer used in everyday modern Korean but remain part of scholarship and international encoding standards. The term jamo thus designates both the fundamental letters of Korean orthography and the broader set used in linguistic description.