How to start learning how to write API in PHP(Phalcon)?

Question

API

Hey!
Please tell me where to start, what knowledge I need to master in addition to the framework and programming language in order to competently write an API that will interact with the frontend (React)?
No, the question is not about React. I am planning to write some project for myself, I want to use Phalcon and React in it. On Phalcon, I need to write an API that should handle everything, etc.
I want to write a professional big blog!)
The issue of data protection worries me a little, but experience shows that this is due to the fact that I have not worked yet, or rather, I have not been involved in API development.
Just consult, give advice, where should I start? Please write step by step.
Thank you very much in advance!

Answer 1

The most important thing is not to trust the user, as well as to check for the right to act. This actually covers most of the security.