Why Do We Shake Hands With Strangers?

Why do strangers clasp hands when they meet? The popular story that a handshake began by proving you held no weapon is appealing, but it is not a proven origin. We follow ancient hand-clasping as a sign of pledge or agreement, later greetings in northern Europe, merchant deals, Quaker practice, and the etiquette that made handshakes ordinary. COVID briefly disrupted the habit, revealing how much a greeting depends on shared expectations.