shí is the everyday reading — to know and knowledge: 认识 (to know a person), 知识 (knowledge), 意识 (consciousness). A separate zhì reading means 'to mark or record' and survives mainly in 标识 (a sign or marker). 认识 is among the first verbs learners meet.
The speech radical, a left-side simplified form of 言. It places 识 in the language family — in classical thought, knowing is bound up with naming, so characters with this radical cluster around speech and identification, like 说 and 认.
只 supplies the sound in the simplified form (traditional 識 used a fuller phonetic). After the reform 只 was chosen as a graphic shortcut; the sound shifted from zhǐ to shí, the central reading of the character.
