A web server is a program using client/server model and www’s (World Wide Web) HTTP (Hypertext Transfer Protocol). HTTP serves the files as web pages from web server that can refer the combination of hardware (computer) and softwares (Computer application) that helps to transfer/deliver Web contents to the user requests through Internet using HTTP/HTTPS.
In today’s world web servers come as a large package of Internet and Intranet. Web servers related programs are- serving e-mail,downloading request for any kind of File Transfer Protocol (FTP) files and of course make and publishing a web sites. Web servers are able to handle security, server-side programming, search engines, publishing and site building tools.
To make a computer in server every computer must contains internet. Those computers are web server and contains a Web site must have some application server program. There are two most popular web servers in now a days-Apache and IIS.
Apache: Apache is the most widely installed .
IIS: Microsoft’s Internet Information Server refers to IIS.
There are others like Novell’s Web Server for users. NetWare operating system and IBM’s family of Lotus Momino servers. Primarily for IBM’s OS/390 and AS/400 users.