A Nix terminology primer by a newcomer
I don't believe I'm the only one to mention the documentation is lacking a little finish. What I personally find is that there's just a lot Nix allows you to do, and no two people do things the same way. On top of this, the official Nix manual may try to teach you a whole bunch of things you won't be using in practice.
This post is an attempt to help smooth the road a bit. What I will try to do is go through Nix terminology bottom-up, and hopefully explain concepts that way. But this will be very much from my perspective, and will contain some opinion as well.
Source: A Nix terminology primer by a newcomer, an article by Stéphan Kochen.