handshake

A handshake is a customary gesture in which two people grasp each other’s right hands and move them briefly. It serves as a greeting, a farewell, a sign of agreement, or a token of mutual trust.

Origin and cultural variation: The practice is widespread across many cultures, with roots likely in ancient rituals of sealing alliances and peace. Practices vary in form and meaning: in some regions a firm grip signals confidence, in others a lighter grasp or an avoidance of touch is preferred. Duration commonly ranges from one to three seconds; eye contact and a brief smile are often expected. Handshakes may be avoided in certain religious or cultural contexts or for health reasons.

Etiquette and dynamics: A handshake typically occurs when approaching at roughly arm’s length, followed by a firm yet comfortable grip and a prompt release. Verbal greetings often accompany the gesture. The nondominant hand may rest at the side or lightly touch the partner’s arm to convey warmth. Social norms regarding eye contact, body orientation, and the use of the left hand vary by culture and situation, including in professional or ceremonial settings.

Technical use: In computing and telecommunications, a handshake describes the initial exchange that establishes a channel, negotiates capabilities, and authenticates participants. Notable examples include the TCP three-way handshake (SYN, SYN-ACK, ACK) that opens a connection, the TLS handshake that negotiates encryption, and device pairings such as Bluetooth or USB authentication.