What is handshaking in networking?

A handshake in networking happens when a computer wants to talk to another computer. Before anything is sent and received the hand shake takes place. This example is from the TCP protocol: Machine 1 sends a SYN packet to Machine 2 Machine 2 sends a SYN/ACK back to Machine 1 Machine 1 sends an ACK back to Machine 2 SYN = Synchronise ACK = Acknowledge