One of the most exciting events in 2015 in the PHP world was the release of PHP 7, 10 years on from the release of the last major version, PHP 5. With a major step forward, PHP 7 introduces plenty of new features and performance upgrades.
However, it also removes old, deprecated functionality, which introduces some compatibility breaks, making it harder for older applications to migrate to the new version. This guide should serve as a quick tour on what to expect if you plan on moving your existing applications, or building new ones, on top of PHP 7.