己 almost always appears in 自己 (oneself). Don't confuse with similar characters: 已 (yǐ, already) — closed top; 巳 (sì, 6th Earthly Branch) — fully closed.
Components
pictograph
己jǐ
self; the 6th heavenly stem
Three-stroke 己 is its own Kangxi radical and not further decomposable. The oracle-bone graph depicts a coiled silk thread or knotted cord — possibly used as a personal mnemonic tally, which gave rise to the 'self' meaning. Visually distinguish 己 (open at top right) from 已 (yǐ, half-closed) and 巳 (sì, fully closed).
Radical
SelfKangxi #49
Pictograph of a coiled silk thread — borrowed early to write 'self' and the sixth Heavenly Stem. As an indexing radical it covers a small group including 已 (already), 巳 (6th Earthly Branch), 巷 (alley), and 巴 (cling to). Productivity is low; use it mainly for character lookup.
