When a connection is established by a client. The client can send data. In the current example the client sends the message "Hi my server". To terminate the connection, the client sends the message "bye". Then the server sends the message "bye" too. Finally the connection is ended and the server waits for an other connection. The two programs should be runned in the same machine. however if you want to run them in two different machines, you may simply change the adress "localhost" by the IP adress of the machine where you will run the server.