PHP was originally developed by Rasmus Lerdorf back in 1994 as part of his work on a series of Perl scripts he was using to maintain he own website.

In 1995, he released these tools as the "Personal Home Page / Forms Interpreter" (PHP/FI) with included support for web forms and database communication.

By 2004, version 5 of PHP was released and would go on to become one of the most widely used web technologies. A more secure version was planned, version 6, but this was eventually abandoned when it proved hugely problematic. PHP moved instead to a new engine with series 7.xx
—David Dwyer (October 23, 2018) PHP: a history and why PHP7 matters Linkedin Pulse


The year 2014 is considered the official start of works on PHP 7. The basis of the version was an experimental branch, the PHP NG (Next Generation), which was designed to optimise performance. The developers worked to refactor the code in order to reduce memory consumption and increase said performance. They sure achieved their goal. Benchmarks for PHP 7 show twice the speed of PHP 5.6 and 50% less memory consumption.
—Rafał Węglarz (October 10, 2020) PHP : Version History
PHP 7.0.0 comes with a new version of the Zend Engine, numerous improvements and new features such as : improved performance (PHP 7 is up to twice as fast as PHP 5.6); significantly reduced memory usage.

The migration guide is available in the PHP manual. Please consult it for the detailed list of new features and backward incompatible changes.

The release being introduced is an outcome of almost two years development journey.
— PHP 7.0.0 Release Announcement