Apache

The Apache HTTP Server, commonly referred to as Apache, is a web server notable for playing a key role in the initial growth of the World Wide Web. In 2009 it became the first web server to surpass the 100 million web site milestone. Apache was the first viable alternative to the Netscape Communications Corporation web server (currently known as Sun Java System Web Server), and has since evolved to rival other Unix-based web servers in terms of functionality and performance. The majority of web servers using Apache run the GNU/Linux OS.

Apache is 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, Mac OS X, Microsoft Windows, OS/2, TPF, and eComStation. Released under the Apache License, Apache is characterized as free and open source software.

Since April 1996 Apache has been the most popular HTTP server on the World Wide Web. As of March 2009 Apache served over 46% of all websites and over 66% of the million busiest.

Apache is primarily used to serve both static content and dynamic Web pages on the World Wide Web. Many web applications are designed expecting the environment and features that Apache provides.

Apache is the web server component of the popular LAMP web server application stack, alongside Linux, MySQL, and the PHP/Perl/Python programming languages.

Apache is redistributed as part of various proprietary software packages including the Oracle Database and the IBM WebSphere application server. Mac OS X integrates Apache as its built-in web server and as support for its WebObjects application server. It is also supported in some way by Borland in the Kylix and Delphi development tools. Apache is included with Novell NetWare 6.5, where it is the default web server. Apache is included with many Linux distributions.

Apache is used for many other tasks where content needs to be made available in a secure and reliable way. One example is sharing files from a personal computer over the Internet. A user who has Apache installed on their desktop can put arbitrary files in Apache's document root which can then be shared.

Programmers developing web applications often use a locally installed version of Apache in order to preview and test code as it is being developed.