Documentation for Frappe JS & Python APIs?

First of all, I would like to thank the leaders and community behind driving this great product; thank you all!

I am new to Frappe/ERPNext development, and I am struggling to find my way to the official documentation of the Frappe APIs to develop server and client controllers.

Where can I find them?
What is the best resource to learn after grassping the basics in the user manual and tutorials?

You can basic functions here.

Structure and development approach:

For the rest of the information you have to find it own.

This is the python 2.7 API