左 combines the left-hand symbol ナ (a stylized left palm) with 工 (carpenter's square / tool). The encoding: while the right hand wields the main tool, the left hand supports it — so 左 originally meant both "left" and "to assist". The "assist" sense was eventually delegated to a derived character 佐 (亻 + 左) so 左 could focus on direction alone. Identical across 繁體 / 新字体 / 简体.

左 and 右 form one of the cleanest oppositional pairs in the script. Both share the upper hand-shape but differ in what sits below — 工 (tool) for left, 口 (mouth) for right. The encoding reflects an ancient observation about handedness: most people's left hand assists tools, while the right speaks for them.

The stroke order matters culturally and pedagogically: in 左, the horizontal stroke is written FIRST, then the diagonal — which is the reverse of 右. Calligraphy teachers drill this difference because it determines whether the character looks balanced.

Mandarin: zuǒ, dipping 3rd tone. 左 (zuǒ, left), 左边 (zuǒbiān, left side), 左右 (zuǒyòu, left-and-right / approximately — a common qualifier: 五点左右 = "around five o'clock"). The character also names political left-wing: 左派 (zuǒpài), borrowed in the 19th century from European political vocabulary.

Japanese: on-reading サ (sa) in 左右 (sayū, left-right), 左折 (sasetsu, turning left). Kun-reading ひだり (hidari) is the everyday word — 左 (hidari, left), 左手 (hidarite, left hand), 左側 (hidarigawa, left side). Driving in Japan is 左側通行 (left-side traffic) — the British inheritance — which makes ひだり essential vocabulary for visiting drivers.

Memory aid: hand on top + tool below. The hand that helps the tool-holder.