This manual describes how to install, use and extend NixOS, a Linux distribution based on the purely functional package management system Nix, that is composed using modules and packages defined in the Nixpkgs project. Additional information regarding the Nix package manager and the Nixpkgs project can be found in respectively the Nix manual and the Nixpkgs manual. If you encounter problems, please report them on the Discourse, the Matrix room, or on the #nixos channel on Libera.Chat. Alternatively, consider contributing to this manual. Bugs should be reported in NixOS’ GitHub issue tracker. Commands prefixed with # have to be run as root, either requiring to login as root user or temporarily switching to it using sudo for example.