The Apache HTTP server is extremely popular and is the world's most used web server software currently. It enjoys the support of the open source community because it is developed and maintained by an open community of developers under the umbrella of the Apache Software Foundation. Although most commonly used on a Unix-like system, it is available for a variety of other operating systems including Microsoft Windows. In 2009, it became the first web server to be used by more than a hundred million websites and currently it is estimated to serve over 50 percent of all websites and 37 percent of the top servers across domains.
One of the reasons it is so popular is that it supports a wide variety of features and many more features can be implemented as compiled modules that can extend the core functionality. For example, on its own, Apache can serve HTML files over HTTP, but with additional modules installed, it can also serve web pages using languages...