{
  description = "Alex's super mega awesome nixos config";

  # A flake's inputs specify the dependencies that get pulled in. Each input is pinned to a specific version (the git commit) of that dependency.
  inputs = {
    nixpkgs.url = github:NixOS/nixpkgs/nixos-unstable;

    home-manager = {
      url = "github:nix-community/home-manager";
      inputs.nixpkgs.follows = "nixpkgs"; # This flake also takes in nixpkgs as its own input, so we can override it here to ensure the same pkgs are used!
    };

    firefox-addons = {
      url = "gitlab:rycee/nur-expressions?dir=pkgs/firefox-addons";
      inputs.nixpkgs.follows = "nixpkgs";
    };

    atau-nixpkgs = {
      url = "git+https://git.atauno.com/atau/atau-nixpkgs?ref=main&rev=751d0b3fd668981d3e69cf8f907a859659122074";
      inputs.nixpkgs.follows = "nixpkgs";
    };
  };

  outputs = { self, nixpkgs, home-manager, firefox-addons, atau-nixpkgs, ... }@flake-inputs:
    let
      pcUser = "alex";
      pcSystem = "x86_64-linux";

      overlays = [
        atau-nixpkgs.overlays.default
        (final: prev: {
          firefox-addons = firefox-addons.packages.${pcSystem};
        })
      ];

      # This helper function generates a nixos system for a linux PC setup. It defaults the username, architecture, and flake inputs if not provided.
      mkPcSystem = { user ? pcUser, hostname, system ? pcSystem, inputs ? flake-inputs }: nixpkgs.lib.nixosSystem {
        inherit system;
        modules = [
          ({ config, pkgs, ... }: { nixpkgs.overlays = overlays; })
          ./config/hosts/${hostname}
        ] ++ (import ./config/modules/home-manager.nix {
          inherit system home-manager user;
        }).modules;
      };
    in
    {
      nixosConfigurations = {
        ## ---- personal computers (linux) ----
        nixos76 = mkPcSystem { hostname = "nixos76"; };
        thelio76 = mkPcSystem { hostname = "thelio76"; };

        ## ---- servers ----
        ursa-minor = nixpkgs.lib.nixosSystem {
          system = "aarch64-linux";
          modules = [ ./config/hosts/ursa-minor ];
        };
        ursa-major = nixpkgs.lib.nixosSystem {
          system = "aarch64-linux";
          modules = [ ./config/hosts/ursa-major ];
        };
        atauno = nixpkgs.lib.nixosSystem {
          system = "aarch64-linux";
          modules = [ ./config/hosts/atauno ];
        };
      };
    };
}