PHP, which is an initialism for PHP: Hypertext Preprocessor, is among the most popular multi-paradigm programming languages out there. Any website or web-based app built on PHP will run on a given web server on the condition that a PHP module is installed, which makes the language truly universal and it isn’t that surprising that there are a few million servers that support it and 100s of millions of PHP websites hosted on them. PHP is preferred over HTML due to the fact that it enables you to set up a responsive site with a huge number of options. A PHP-based social network, for instance, will show different content to each visitor despite the fact that the URL will stay unchanged. By contrast, HTML-based sites are static and the page content itself can be edited only manually. Like any other software, PHP has several versions and the one that was used while developing a given website must be available on the server in order for the site to work correctly.