Hangul syllable jjas

Shift+W starts ㅉ; K adds ㅏ, and T adds final ㅅ.

In Korean input mode, Shift+W enters the tense initial ㅉ, K enters ㅏ, and T enters final ㅅ. The input method editor combines those components into 짯. Here, ㅉ is the tense consonant, ㅏ is the Korean vowel “a,” and ㅅ closes the syllable.

Where does this kind of Hangul block come from?

Hangul was designed to write Korean speech with its own letters.

Hunminjeongeum, the name for the new writing system, appears in King Sejong’s records in 1443. A guide explaining how it works followed in 1446, describing how the letters form syllable blocks. The system let people write Korean speech directly rather than relying only on Chinese characters used in formal writing.

Earlier Korean writing also adapted Chinese characters through systems called idu, gugyeol, and hyangchal. Some scholars have proposed that Hangul’s design was influenced by the Mongolian Phags-pa script; that remains a debated possibility, not a proven direct ancestor. In the late 19th and early 20th centuries, Hangul’s public role was reconsidered alongside Hanja (Chinese characters used in Korean writing) and Hanmun (classical Chinese writing).