The most popular form of interprocess communication involves message passing .
Processes communicate with each other by exchanging messages.
A process may send information to a port , from which another process may receive information. The sending and receiving processes can be on the same or different computers connected via a communication medium. One reason for the popularity of message passing is its ability to support client-server interaction. A server is a process that offers a set of services to client processes. These services are invoked in response to messages from the clients and results are returned in messages to the client.