Most web applications (and all eXtropia web applications) rely on a web
server to perform the requested job.
For example, when a client using a web browser like Internet Explorer or
Netscape Navigator submits a search on a website, it is the web server
that actually performs the search behind the scenes.
The web server itself has both hardware and software components.
However, in common usage, when most people use "Web server", they are
referring to the web server software that runs on the web server hardware.
The market leading web server software is Apache. The competitors to
Apache include Microsoft Internet Information Server (IIS) and the
Netscape Web Server.