These sections are designed to give some background information on what Nix is. If you've never heard of Nix before looking at Nixery, this might just be the page for you!
Nix is a functional package-manager that comes with a number of advantages over traditional package managers, such as side-by-side installs of different package versions, atomic updates, easy customisability, simple binary caching and much more. Feel free to explore the Nix website for an overview of Nix itself.
Nix uses a custom programming language also called Nix, which is explained here on its own page.
In addition to the package manager and language, the Nix project also maintains NixOS - a Linux distribution built entirely on Nix. On NixOS, users can declaratively describe the entire configuration of their system and perform updates/rollbacks to other system configurations with ease.
Most Nix packages are tracked in the Nix package set, usually simply
referred to as
nixpkgs. It contains tens of thousands of packages already!
Nixery (which you are looking at!) provides an easy & simple way to get started with Nix, in fact you don't even need to know that you're using Nix to make use of Nixery.