The API Reference will give you access to descriptions of all API calls available, i.e.
- which methods are available
- what parameters must/can be passed
- what results are to expect
Its intention is to help developers to find a) the suitable methods and b) their syntax.
One disclaimer in advance: Other than Java programmers, PHP programmers tend to ignore the difference between public and private objects (in most object oriented languages ignorance does not help, since the private objects simply cannot be accessed publically). Though in PHP you technically can access private objects in public context, you are strongly advised not to do so: While I do my very best to keep all public interfaces compatible to previous versions, I will never guarantee this for objects (methods, properties) which are explicitly marked private. So please stick to the public ones mentioned in the API reference. Everything the API reference refers to as "private" is private. As well is anything the API reference does not mention at all, but you (may) find in the code.