PHP ships a new minor version every November. Each branch gets two years of active support (bug and security fixes, point releases about every four weeks) and two more years of security fixes only, then reaches end of life. Point releases add no language features, so 8.5.4 to 8.5.10 is a safe update; a minor upgrade (8.4 to 8.5) can deprecate things and needs testing. php.net lists:
| Branch | Released | Active support until | Security fixes until | Latest release |
|---|---|---|---|---|
| 8.2 | 8 Dec 2022 | 31 Dec 2024 | 31 Dec 2026 | 8.2.33 (30 Jul 2026) |
| 8.3 | 23 Nov 2023 | 31 Dec 2025 | 31 Dec 2027 | 8.3.33 (30 Jul 2026) |
| 8.4 | 21 Nov 2024 | 31 Dec 2026 | 31 Dec 2028 | 8.4.25 (27 Aug 2026) |
| 8.5 | 20 Nov 2025 | 31 Dec 2027 | 31 Dec 2029 | 8.5.10 (27 Aug 2026) |
PHP 8.1 and everything older is end of life (the last 7.x release was 7.4.33, on 3 November 2022): the PHP project no longer patches them, and only paid long-term-support vendors do.
This book targets PHP 8.5 because it is the newest stable branch, with the longest support, and what Ubuntu 26.04 225 LTS ships. Laravel 13 2,157 supports PHP 8.3 to 8.5, so Laravel runs on the same interpreter. And the test tools have already left older branches behind: PHPUnit 13 79,198 requires PHP 8.4.1 or later, and Pest 5 requires 8.4 (Setting Up PHPUnit). Features are dated where they appear, so on an 8.3 server you can see what you may use.