Android client-server (sharing, saving). How to organize?

Question

PHP

All the best!
I tried to find the material to start with, and just drowned in diversity, and the presence of old information (like asynctask) is even more frightening.
The plans are to make a simple multiplayer turn-based game. The client will be on android. At the moment, I am writing the code in pure JAVA in order to see how it all will work in text form (now the command line interface)))
Why do I need a client server:
1) keeps a history of moves 2) makes changes to the data of different users (users no more than five) 3) sends general data to other users.
What is relevant to use for this? I'm interested in how to organize the server side. I beg you to give links to the manuals or explain a little.
PS: Many advise Retrofit... as I understand it in JAVA. (this is apparently my misunderstanding, I thought Retrofit is a server). But I would like to use PHP (server), in view of its versatility. I will gladly listen to your advice.

Answer 1

The first thing I realized is that I need to do registration-authorization in PHP by studying what http headers are and how cookies work. A bit of practice with POST and GET requests - what and how goes into the PHP script, and what comes back. Hike still get acquainted with the basics of SQL, tk. accounts will be stored there.
After registration and authorization, POST requests will send the necessary data to the server.

Answer 2

Nobody prevents you from making a server even in PHP, even in Java, even in python, ruby, c ++ or something else. With great probability, someone will come running and advise Javascript, because it is in fashion now.
Recommending something specific without describing requirements is a waste of time.
The universal answer: take the language you know or the one you want to learn.