PHP7-Reference - An overview of the features, changes, and backward compatibility breakages in PHP 7
PHP 7 was released on December 3rd, 2015. It comes with a number of new features, changes, and backwards compatibility breakages that are outlined below. Unarguably the greatest part about PHP 7 is the incredible performance boosts it provides to applications. This is a result of refactoring the Zend Engine to use more compact data structures and less heap allocations/deallocations.