You can install NixOS on physical hardware by burning one of the CD
images onto a blank CD/DVD disk, or by
copying it onto a USB stick. For installation
instructions, please see the manual.
Graphical ISO image
The graphical installation ISO image contains NixOS
installer as well as Desktop Environment
and several applications. It’s a live CD, so it allows you
to get an impression of NixOS (and the Nix package manager) without
installing it.
The minimal installation ISO image does not contain the
graphical user interface, and is therefore a lot smaller.
You have to run the installer from the console. It
contains a number of rescue tools.