Apache HTTP server is an open-source, cross-platform web server application which can power a wide range of web services. Originally developed for the UNIX environment, Apache HTTP Server was later ported to different platforms including Linux, Windows and others. Apache HTTP server has remained the most popular web server as of today. There is a large collection of Apache HTTP Server plug-in modules and add-ons, extending its functionality in terms of security (e.g., SSL/TLS/LDAP-based authentication, access control, intrusion detection), server-side programming language support (e.g., PHP, Python, Perl, Ruby on Rails), request handling (e.g., filtering, compression, URL rewriting), protocols (e.g., IPv6, HTTP/2, FTP), network policies (e.g., bandwidth/connection throttling, IP geolocation), etc.