How to haxx/crack

[Funqadelic]

Hi there, i've always been curious to how people manage to get hold to other people's accounts on let's say Netflix or any other website where you need to pay for their streaming services. Are you using some sort of program? Or is it a virus? It's always been a mystery to me. I mean, I guess we're committing a crime? Kind of? But it's funny as hell.
Thx