Definition Web server

A Web server  is a program that, using the client/server  model and the World Wide Web's Hypertext Transfer Protocol (HTTP), serves the files that form Web pages to Web users (whose computers contain HTTP clients that forward their requests). Every computer on the Internet that contains a Web site must have a Web server program. Two leading Web servers are Apahe , the most widely-installed Web server, and Microsoft's Internet Information Server ( IIS ). Other Web servers include Novell's Web Server for users of its NetWare operating system and IBM's family of Lotus Domino servers, primarily for IBM's OS/390 and  AS/400 customers.