Common programming paradigms:

Procedural: Code is organized into procedure calls (methods/functions/etc). Code executes one line at a time, and when a procedure call is found, current state is saved to the stack and execution jumps to the code in the procedure. When the procedure is done, the stuff on the stack is popped off and execution jumps back to the line following the procedure call.

Object oriented: like procedural except that methods and state are organized into objects. Each object is responsible for some chunk of functionality and hides the implementation thereof.

Functional: a paradigm in which functions are first class objects, think lambdas, etc. Too complicated to explain here.

If I remember from so many years ago, to say some algorithm is O(f(n)) means that after some minimum input size c, the algorithm's execution time does not grow faster than than f(n).

Agreed. As a Linux Guy who got pulled into Windows development, I do miss having VS. The debugger alone makes it worth using--way more productive than gdb.

Free as in speech (open source): no.

Free as in beer: partially (for everything but enterprise development, IIRC)

https://en.m.wikipedia.org/wiki/Gratis_versus_libre