How to create registration and authorization?

Question

Android

Hello! What knowledge is needed in order to register and log in to an android application? You can throw articles on how to implement all this.
Ps. Registration through third-party servers (google fb, etc.) is not of interest, you just need to understand how to do it all yourself

Answer 1

Absolutely different knowledge is needed - backend development. So different people do it.
Hire an outside person to implement the REST API (+ OAuth).
But if you want, then in 3 months you can master Ruby On Rails, this is the easiest of the options.

Answer 2

How to build a request using which protocol to send

Using the HTTP protocol.
The simplest example, let's say a PHP script on the server is available at test.ru/test.php (the file is available in the browser because the browser is an HTTP client, the browser's address bar sends an HTTP GET request)
Here is the content of this file:

<?php

echo "Hello World";

?>

Moreover, it is possible even without PHP, just a text file with the content "Hello World" available at the address, you can also make HTTP GET requests to it through the server.
After you have created such a test server, the task of your application is to send an HTTP request and receive a response, there is information on this topic on the Internet.