PHP 8.4 is the active development branch and the current target for new feature and major changes and new RFCs. Scheduled for general availability on 2024.
PHP 8.3 is the upcoming PHP version, bringing typed class constants, Granular DateTime Exceptions, fallback value support for PHP INI Environment Variable syntax, and more.
PHP 8.2 is the latest PHP version which brings readonly classes, DNF types, null, false, and true types, sensitive parameter redaction support, a new random extension, and several new features along with a few deprecations.
PHP 8.1, released in 2021, brings major new features such as Enums, Fibers, never return type, Intersection Types, readonly properties, and more, while ironing out some of its undesired legacy features by deprecating them.
PHP 8.0, on the 25th year of PHP history, brings several important features such as Union Types, JIT, Constructor Property Promotion, Match Syntax, Named Parameters, and several more performance, syntax, and quality-of-life improvements.