The word 打招呼 is formed by combining three characters that visually and conceptually depict the active process of initiating a social greeting: 打 (dǎ, to strike/hit) here implies the act of "making" or "doing", 招 (zhāo, to beckon/signal) captures the physical gesture like a wave or nod, and 呼 (hū, to call out) represents the verbal component of hailing someone. Together, they create a vivid, miniature scene of the complete action, actively signaling and calling out to someone, which metaphorically condensed into the single, unified concept of "to greet".