For example, the common phone system that we are all accustomed to uses an agreed upon protocol. When a person wishes to initiate a communication the first person enters the number associated with the phone of the second person. This is how the second person knows that someone desires to communicate. The second person then picks up the receiver and says 'Hello' to indicate that the first person may now begin to speak. The termination of the connection is initiated by one person saying the word 'Goodbye' and is confirmed via a like sign from the other person.
Computer protocols work in much the same way.
The difference is that in the phone system, once a phone connection is established we no longer need to use the phone number during the conversation. Probably the most frequently used protocol, TCP , uses the IP protocol but is itself a connection-oriented protocol. In addition to its IP address every computer on the Internet may have a name called a host name . Host names are mostly for the convenience of human beings. They are easier to remember than IP addresses and provide a means of better organizing computers within an organization.