Asynchronous Socket Programming in C#: Part I – CodeGuru

Objective

The objective of this article is to demonstrate a socket-based client/server application that will allow two-way asynchronous communication between a server and multiple client applications. Because this example uses asynchronous methods, the server application does not use threads to communicate to multiple clients (although internally the asynchronous communication mechanism uses threads at the OS level).
The Difference Between Synchronous and Asynchronous Communication in Network Programming