A handshake is a short ritual

Ritual

A ritual is a set of actions, performed mainly for their symbolic value. It may be prescribed by a religion or by the traditions of a community. The term usually excludes actions which are arbitrarily chosen by the performers....

 in which two people grasp one of each other's like hands, in most cases accompanied by a brief up and down movement of the grasped hands.
Archaeological ruins and ancient texts show that handshaking was practiced in ancient Greece

Ancient Greece

Ancient Greece is a civilization belonging to a period of Greek history that lasted from the Archaic period of the 8th to 6th centuries BC to the end of antiquity. Immediately following this period was the beginning of the Early Middle Ages and the Byzantine era. Included in Ancient Greece is the...

 as far back as the 5th century BC; a depiction of two soldiers shaking hands can be found on part of a 5th century BC funerary stele

Stele

A stele , also stela , is a stone or wooden slab, generally taller than it is wide, erected for funerals or commemorative purposes, most usually decorated with the names and titles of the deceased or living — inscribed, carved in relief , or painted onto the slab...

 on display in the Pergamon Museum

Pergamon Museum

The Pergamon Museum is situated on the Museum Island in Berlin. The site was designed by Alfred Messel and Ludwig Hoffmann and was constructed in twenty years, from 1910 to 1930. The Pergamon houses original-sized, reconstructed monumental buildings such as the Pergamon Altar and the Market Gate...

, Berlin (stele SK1708) and other funerary steles like the one of the 4th century BC which depicts Thraseas and his wife Euandria handshaking (see images on the right).