PHP 7.4 upgrade guide: typed properties, arrow functions, variance, ??=, spread in arrays, WeakReference, __serialize/__unserialize, OPcache preloading, FFI—and the BC breaks that hit real apps.

Explore PHP 8.0 after 7.4: named arguments, match, nullsafe, attributes, JIT, union types—what breaks, what to rewrite, and runnable examples.

PHP 8.1 after 8.0: enums, readonly properties, fibers, intersection/never types, first-class callables—plus $GLOBALS rules, MySQLi exceptions, and a deprecation watchlist.

PHP 8.2 guide: readonly classes, standalone null/false/true types, DNF types, #[SensitiveParameter], Random extension, dynamic property deprecations, and BC breaks from 8.1.