A stage tarball is an archive of the basic files and packages used for the installation of Gentoo Linux.
Stage 3 tarballs are the ones used for installation when following the Handbook, and will usually be the only sort most users will deal with. Stage 3 tarballs are the only ones offered to be downloaded.
A stage3 tarball is an archive containing a profile-specific minimal Gentoo environment. Stage3 tarballs are used to install Gentoo.
Downloading and decompressing a stage 3 tarball as described in Gentoo Handbook will install an almost-complete and almost-functional system (the most important parts still missing are a kernel and a bootloader).
The desktop profile stage 3 tarballs provide extra packages to help setup desktop systems more easily. If planning on installing a desktop system, using a desktop profile, choose the corresponding archive.
Stage 3 tarballs are compiled from stage 2 tarballs, but contain a system set of packages.
Not including sub-profiles, the base file used for the system set of all profiles can be found at: /var/db/repos/gentoo/profiles/base/packages.
A "stage 4" tarball is a loosely defined term that generally just means a stage3 with 'extra bits'.
Official "stage 4" tarballs became available in January 2016 for the amd64 architecture, but are no longer available.
A cloud "stage 4" has been created to aid in the process of virtual machine provisioning. These stage 4 files can be used with diskimage-builder (available via app-emulation/diskimage-builder). See the Gentoo README upstream and official diskimage-builder documentation for more information.
mkstage4 can be used to help create a "stage 4" tarball.
Catalyst is also another tool for power users to deploy Gentoo to multiple machines.
Internal development tarballs
These tarballs are only usually used by Gentoo developers to bootstrap the system for release, and are generally not intended for end users.
Being mostly for internal use, there are no stage 1 or stage 2 tarballs available for download.
Stage 1 tarballs are generated from a packages.build file. Each system profile may have a slightly different packages.build file:
Stage 2 tarballs contain the same packages as a stage 1 tarball with one caveat: stage 2 tarballs are compiled from a stage 1 tarball. This is to ensure the stage 1 tarball contains the tool chain necessary to reproduce itself.
- Bootable media — images available for download
- Installation — an overview of the principles and practices of installing Gentoo on a running system.
- https://www.gentoo.org/downloads/ - Gentoo download page with stage tarballs