# phpinternalsbook/PHP-Internals-Book

PHP Internals Book

Repository: https://github.com/phpinternalsbook/PHP-Internals-Book
Canonical: https://ross.abutalabs.com/products/php-internals-book
Homepage: http://www.phpinternalsbook.com/
Language: Python
License: NOASSERTION
License Family: other
Last push: 2026-07-09T18:55:08+00:00

## Health v2 (maintenance only)
Score: 73/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 91, release rhythm 35, longevity 100
- inputs: {"age_days": 5119, "days_push": 55, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: no_releases, no_license
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1436, forks 179 (observed 2026-08-28T04:04:43.638702+00:00)

## What it is
An open-source online book explaining the internals of PHP 7 and PHP 8, covering the build system, zvals, memory management, and C extension development. It is written in ReStructured Text and built with Sphinx, published at phpinternalsbook.com.

## Use cases
- learn how the PHP engine works internally
- learn how to write PHP extensions in C
- understand zval and memory management in PHP
- build PHP from source for development
- debug PHP memory issues with valgrind
- understand PHP arrays and Hashtables implementation

## When to choose
- you are developing or maintaining PHP extensions in C
- you want deep understanding of the Zend engine, zvals, and memory management
- you need to compile PHP from source for core development

## When to avoid
- you want to learn PHP application programming rather than internals
- you need a quick reference rather than in-depth tutorial material

## Facets
- artifact type: learning-resource
- maturity: active
- function: documentation
- domain: programming-languages, tutorials, developer-tools
- platform: cross-platform
- tags: php, php-internals, sphinx, book, c-extensions, zend-engine

## Member repositories
- phpinternalsbook/PHP-Internals-Book (main) score 73

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:04:43.638702+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T04:36:48.768545+00:00, confidence not recorded.
  - readme: https://github.com/phpinternalsbook/PHP-Internals-Book (fetched 2026-08-28T04:04:43.638702+00:00, sha b4efb0ba6e64)
  - homepage: http://www.phpinternalsbook.com/ (fetched 2026-08-29T11:47:50.540590+00:00, sha 4b76a1f5a321)
  - site_page: https://www.phpinternalsbook.com/php7/build_system/building_php.html (fetched 2026-08-29T11:47:50.543412+00:00, sha d55a7536436c)
  - site_page: https://www.phpinternalsbook.com/php7/build_system/building_extensions.html (fetched 2026-08-29T11:47:50.545912+00:00, sha 39b4b9ebf722)
  - site_page: https://www.phpinternalsbook.com/php7/extensions_design/extension_infos.html (fetched 2026-08-29T11:47:50.547899+00:00, sha 345ce65cffce)
  - site_page: https://www.phpinternalsbook.com/php7/memory_management/memory_debugging.html (fetched 2026-08-29T11:47:50.549728+00:00, sha 85f11b9db368)
- Data as of 2026-08-30T08:39:29.467469+00:00.