PHP is a common open source general-purpose programming language. PHP is designed specifically for Web development and its code can be embedded in HTML and generate HTML code that is sent to the client. The very first version of PHP was created by Rasmus Lerdorf in 1994 and was a set of tools for tracking Web page visitors. Over time, PHP has evolved from a small set of tools into a full-fledged programming language, and its name was changed as a recursive entity PHP HyperText Preprocessor.
There are several versions of PHP and currently PHP 7 is the major version. In PHP 5, all XML extensions have been rewritten to use a different set of tools provided by libxml2. It is a feature-rich library that effectively implements XML standards, providing the advanced capabilities of XML technology in PHP. PHP is quite easy to learn, but, in turn, is able to satisfy the needs of professional programmers.
PHP syntax is similar to C syntax. Some elements, such as associative arrays and the foreach loop, are taken from Perl. To execute scripts, you do not need to describe any variables, modules, etc. Any program can start directly with a statement The program code is executed if there are <?php ?>delimiters. Everything behind the delimiters is displayed unchanged. This type is mainly used to insert PHP code into an HTML document.