PHP, or PHP Hypertext Pre-Processor, is a server-side Web Development scripting language originally created in 1994. It’s back-end nature allows more secure processes to take place between the server and the browser.
It can securely process login scripts, send emails, and load content from a database.
PHP 5 was released in 2004, which included new features for object-oriented programming of web applications. In 2008, PHP 5 became the only stable version supported, and many scripts needed to be re-written to be supported by the latest version.
During the development of PHP 6, the project ran into some issues, meaning the 6th version got put on hold, and later abandoned in 2010.
PHP 7 was in development during 2014 and 2015, later being officially released in December 2016. PHP 7 includes many WordPress-based performance standards in performance.
I use PHP in the development of WordPress websites, using the wide range of functions available in WordPress to load content, and build custom functions.