Apache is the web server for Linux and other OpenSource, and not so open source operating systems. NCSA's "httpd" which there were a whole heap of patches circulating around and was clearly not being maintained, so a group of developers got all the patches together and did their own version of the web server. Since it was based on a whole heap of patches they called it "A Patchy Server", thus "Apache Server" with it's name.
See Also: RewriteRules, 
http://www.apache.org/
39 pages link to Apache:
