The web – technology as a whole – takes massive leaps ahead. One day you’re happily coding in PHP5.X and the next you hear – PHP7 is out!
Wait! What?! What happened to PHP 6?!
PHP 6 was tabled as a version name/release candidate because it failed in its mission to bring native unicode support to the language. Apparently, doing so made PHP 6 a memory hog and a bear to program in.