This page contains a list of recent versions of PHP. Going further down allows you to see the specific keys for the downloads above. Along with the varying downloads for both Windows and other platforms, going all the way to the bottom of the page allows you to see and download even earlier versions of PHP besides the ones shown, going all the way back to version 5.
This page contains a list of manuals for PHP, ranging from english to spanish, french, russian, japanese, and more. There are also links to various tips and tricks with using PHP, as well as manuals of earlier versions of the language. They also have manuals on how they edit and translate their documentation.
This page gives people an opportunity to contribute to the development of PHP. They list 4 way to help contribute to the language, specifically: running tests, finding and diagnosing failed tests, resolving bug reports, and maintaining/translating documentation on github. Below that is helpful information for people who want to develop the language by using C. There are 4 links below for them, being lxr, RFC, Developer Setup help, and a Mailing List.
In Summary, the PHP site has a collection of downloads available for those who want to use PHP, including downloads that date all the way back to Version 5. Their site includes documentation for the language, in many different languages besides English, and manuals on how they go about editing and translating. And finally, they give testers and developers an opportunity to help develop the language and work with the team that mantains PHP.