The term "web server" sometimes refers to a server computer and
sometimes to the web server software that runs on a server computer.
The purpose of web server software is to receive and respond to
requests for web pages from a web browser running on a client machine.
When the web server receives a requests, it often just needs to send
back a "static" web page. Sometimes, however, it must invoke a
server-side script or application system (sometimes on a different
server computer), obtain the requested data, and insert formatted
information into a dynamically created web page.
There are many different types of web server software. The operating
system (Unix, Linix, Windows, etc) on the server computer determines
what type of web server software can be run. For example, on
Windows computers, IIS (Internet Information Server) software is often
used. On servers running Linux, Apache web servers are very
common.
