TCP Handshake (Three-Way Handshake) : Connection Oriented Service

It is a method used to create connection between client and server in TCP/IP network.

It's simple three step process take place before the actual data communication begins, where client and server exchange SYN and ACK packets.

So, a three-way handshake is primarily used to create a TCP socket connection, it works when:

• First a client node send a SYN packet to server which may or may not be on same network, to talk to server whether it open for new connection or not.
• If server have open port it accept and initiate new connection, so when server receives SYN packet it respond with ACK packet or SYN/ACK packet. Telling client that request has been acknowledged.
• Client receives SYN/ACK packet and respond with an ACK packet .

After completion of this process, the connection is created and client and server can communicate. 

For the same reasons it also refers as connection oriented service where first connection is established before the starting of communication.

A connection oriented service is more reliable the connection-less service because there is no chance of losing data packet while communication.