National Handshake Day is celebrated every year on the last Thursday of June. This year, the special day will be observed on June 29. Handshakes are used to show respect, honor, or warmly welcome someone. Whether meeting a new person or seeing someone you haven't seen in a while, a handshake is a longstanding custom and a friendly greeting.  And if handshakes aren't your style, a fist bump works just as well!