How do URL requests work?

Question

PHP

Good day, I just started to study web technologies, I just want to expand my horizons and make a course)
And I need to make a URL request from the application client (obj-c) to the web server (127.0.0.1/name.php) with sending some data (login/password), process and return the result (JSON).
I don’t understand how to make such a request, here is an example with vk api:

https://api.vk.com/method/METHOD_NAME?PARAMETERS&access_token=ACCESS_TOKEN

I hope you don’t throw slippers at me, but direct me where to dig, otherwise I don’t even know what such requests are called.

Answer 1

Wikipedia first : HTTP
then
Google: objective-c send http request