This chapter is meant to discuss the approach to building server programs. A server program may, or may not have a user-interface in the traditional sense. An example of a server program would be a program that accepts TCP/IP connections and then responded to requests by carrying out some process and then returning a result to the caller. A web server, a dedicated XML server that acts as a gateway to a database, a mail server, a payment gateway, a graphics server that converts images from one format to another, a file update system; these are all typical server programs.