In this tutorial, we will show you how to install PHP 7.3 on Debian 9. PHP (Hypertext Preprocessor) is an open-source server-side scripting language designed primarily for creating dynamic interactive websites. PHP is one of the most popular languages and it is freely available for redistribution and modifications. PHP powers WordPress, the most popular content management system used for blogging and building websites, as well as many other e-commerce websites, customer relationship management software, enterprise resource planning software, and much more.