Learning back end

Question

I want to start learning back end, so, where should I start?

Answer 1

https://www.w3schools.com/php/default.asp
https://w3resource.com/php/php-home.php
https://www.w3schools.com/sql/default.asp
https://www.w3schools.com/nodejs/default.asp
https://www.tutorialspoint.com/nodejs/index.htm
https://www.tutorialspoint.com/ruby/index.htm
http://guides.rubyonrails.org/

Answer 2

Ruby on Rails
Python Django
Node.js

Answer 3

Node.js
Ruby on Rails
Java