Apache, Internet Information Services, lighttpd and Jigsaw Server are four different types of web servers. These software programs run on different operating systems such as Windows, Linux and Mac OS X. Web server programs enable web sites to function, as they process requests from computers accessing the web server and determine how to handle and respond to those requests.
The Apache HTTP Server is a free and open source web server program that is one of the most popular web servers in the world. Apache runs on multiple operating systems including Windows, Linux and Mac OS X.
Microsoft's Internet Information Services web server is included by default with the Windows Server operating systems, and runs only on Windows machines. Internet Information Services is heavily integrated with the Windows operating system, making it straightforward for Windows Server administrators to use it.
Lighttpd is a free and open source web server that is included by default with the FreeBSD operating system. This server is also available for other operating systems including Windows, Mac OS X and Linux. Lighttpd is focused on consuming as few system resources, such as RAM and CPU, as possible.
Jigsaw Server is written in Java and is a basic web server program published by the World Wide Web Consortium. It runs on multiple operating systems and can run basic PHP and CGI files.