着 (zhe) — (particle) indicates an action in progress or a continuing state

着 (zhe) is the aspect particle for a continuing state or ongoing action — as in 坐着 ('sitting') or 看着电视 ('watching TV'). Don't confuse it with 了 (completed action) or 过 (ever-experienced).

Most characters — around four in five — are built this way: one part hints at the meaning, the other at the pronunciation.

This origin belongs to the traditional form 著; 着 is its simplified writing.

The traditional form 著 puts 艸 (grass; plant) above 者, which gives the sound; the simplified 着 is a later shorthand.