Apache Web Server
Apache is web server developed and maintained by an open community of developers under the auspices of the Apache Software Foundation.
The application is available for a wide variety of operating systems, including Unix, GNU, FreeBSD, Linux, Solaris, Novell NetWare, AmigaOS, Mac OS X, Microsoft Windows, OS/2, TPF, and eComStation. Released under the Apache License, Apache is characterized as open-source software.
Since April 1996 Apache has been the most popular HTTP server software in use. As of February 2011 Apache served over 59.13% of all websites and more than 66.62% of the million busiest.