Apache is the most popular Web server software. It enables a computer to host one or more websites that can be accessed over the Internet using a Web browser. The first version of Apache was released in 1995 by the Apache Group. In 1999, the Apache Group became the Apache Software Foundation, a non-profit organization that currently maintains the development of the Apache Web server software.
Apache's popularity in the Web hosting market is largely because it is open source and free to use. Therefore, Web hosting companies can offer Apache-based Web hosting solutions at minimal costs. Other server software, such as Windows Server, requires a commercial license. Apache also supports multiple platforms, including Linux, Windows, and Macintosh operating systems. Since many Linux distributions are also open-source, the Linux/Apache combination has become the most popular Web hosting configuration.
Apache can host static websites, as well as dynamic websites that use server-side scripting languages, such as PHP, Python, or Perl. Support for these and other languages is implemented through modules, or installation packages that are added to the standard Apache installation. Apache also supports other modules, which offer advanced security options, file management tools, and other features. Most Apache installations include a URL rewriting module called "mod_rewrite," which has become a common way for webmasters to create custom URLs.
While the Apache Web server software is commonly referred to as just "Apache," it is technically called "Apache HTTP Server," since the software serves webpages over the HTTP protocol. When Apache is running, its process name is "httpd," which is short for "HTTP daemon."