XAMPP is a completely free, easy to install Apache distribution containing MySQL, PHP, and Perl. The XAMPP open source package has been set up to be incredibly easy to install and to use.
Many people know from their own experience that it's not easy to install an Apache web server and it gets harder if you want to add MySQL, PHP and Perl. The goal of XAMPP is to build an easy to install distribution for developers to get into the world of Apache. To make it convenient for developers, XAMPP is configured with all features turned on. In the case of commercial use please take a look at the product licenses, from the XAMPP point of view commercial use is also free. There are currently distributions for Windows, Linux, and Mac OS X. The most popular PHP dev package and completely free of charge.