Apache HTTP Server is the leading web server software available. It commands nearly 60% of the web server market and over 66% of the 1 million sites with the most traffic. It is developed by the Apache Software Foundation and is released under a free and open source license called the Apache License 2.0.
Because it is free, anyone can download and install Apache on nearly any computer. The software supports numerous platforms, including Linux, Solaris, Novell Netware, Microsoft Windows, and various Unix variants. If you are running a Linux server, Apache is very easy to install. Simply use the software repository provided by your distribution. Nearly all distributions have Apache either installed or provide installable binaries. There are also binaries available for many other operating systems. As a last resort, you can build Apache from source and install it manually.
Apache’s configuration is controlled by a single file, often called httpd.conf or something similar. The file can be configured to refer to other configuration files on virtual server websites and also can refer to .htaccess files on within individual directories of sites. Apache is part of the famous LAMP stack, which refers to Linux Apache MySQL, and PHP. Most major web hosts offer Linux hosting with Apache web servers or Windows-based alternatives.