Appendix

Three reference sections close the book, and each one exists so that you can check rather than trust.

A - Sources lists every figure used in the book, chapter by chapter, with the publisher, the URL, the date the data refers to and the date it was last checked. It closes with the figures I refused, and why.

B - PHP Versions, 2015 to 2026 gives the release date, the support window and the headline changes of every version from PHP 7.0 to PHP 8.5, so that a figure about “PHP 8” can be placed in time.

C - Glossary defines the terms I use that you may not know if you come from another ecosystem.