A handshake is a greeting where two people briefly grasp each other's right hands and move them up and down a few times. When you meet someone new, shake hands with a coach before a game, or congratulate a friend on winning an award, you're using one of the most common gestures of respect and friendliness in many cultures.

A good handshake often involves looking the other person in the eye, gripping firmly (but not too hard), and shaking once or twice. A weak, limp handshake can make you seem unconfident, while crushing someone's hand seems aggressive. People often judge others by their handshakes, viewing a solid handshake as a sign of confidence and trustworthiness.

Today, a handshake can signal agreement, greeting, or farewell. When two people “shake on it,” they're using a handshake to seal a deal or promise, treating the gesture as seriously as a written contract.

The word also appears in technology: a digital handshake describes how computers exchange signals to establish a connection, borrowing the human meaning of “establishing trust and agreement.”