How do people become php internals, or php core developers

I don't understand this actually, does someone taking passing the zend exam makes him/her eligible to become an internal, or core developer?

I am by no means knowledgeable in PHP, but I am curious how people part of php core developers / php internals

 

No, the Zend exam has nothing to do with this. If you want to get involved, test release candidates, find bugs, submit patches, talk to other core devs on IRC, subscribe to mailing lists, etc... PHP's source code is available on Github, so you can send pull requests there.

You also need some C programming skills. There's more on php.net:

http://php.net/get-involved.php
http://php.net/support.php
https://wiki.php.net/internals/references

 

Thanks, more answer than I had asked for.