How to start learning about client-server communication in Android?

Question

Android

There is a desire to write an application for Android with the functionality:
A) Registration / Log-in
B) Similarity to an online store: add goods to the basket and place an order C
, optional) Attach payment.
And the issue is that I have no idea about client-server interaction in general. Where to start studying? How to switch to android?

Answer 1

Start by reading!
vk.com/doc232854130_379492516?hash=405558e82b966c1...