Zend Engine Explained

The Zend Engine is the centerpiece of PHP, and is the component that parses (in other words, 'understands') and executes all of your PHP files.

Work on the Zend Engine began on 1997, when Andi Gutmans and Zeev Suraski designed the first implementation of the PHP language, with syntax loosely based on PHP/FI. Their work on PHP 3 revolutionized the PHP world, and created PHP as we all know it today.

The term 'Zend Engine' was first used in 1999, and was given to the scripting engine of PHP 4. For the first time, the scripting engine was a separable, reusable component, that was not tied to the Web-specific interfaces of PHP in any way, and could be used elsewhere. The performance, reliability and extensibility of PHP 4's engine brought a 2nd revolution to the world of PHP, and helped making it the most popular Web platform in the world today.

The Zend Engine is responsible for the following tasks in PHP:

The Zend Engine was designed to be extensible, and allows extension modules such as debuggers, performance boosters and custom loaders to be dynamically integrated to it. Whenever you're using such a plug-in module, you're doing so thanks to the extensibility options of the Zend Engine!