XAMPP is a free and open source cross-platform web server package that consists of Apache HTTP Server, MySQL, PHP, and Perl. It is available for Windows, Linux, Solaris, and Mac OS and is used for web development projects. XAMPP requires only a single file to download and run with little configuration needed. Installing XAMPP is faster than installing each component separately and allows for multiple instances on one computer. While intended for local development and testing, XAMPP is sometimes used to serve live web pages.