Immutable Linux systems (immutable distros)

In short: With an immutable distribution the base system is read-only. Updates are applied as a whole image and can be rolled back if problems arise.

In more detail: Programs come as Flatpak, container or in layers on top. That makes the system robust and well reproducible.

In detail

• Fedora Silverblue/Kinoite/Atomic: rpm-ostree, Flatpak for applications, Toolbox/Distrobox for development environments.
• SteamOS: read-only image on the Steam Deck.
• NixOS: the whole system is one configuration file (configuration.nix). Every generation can be switched back.
• openSUSE Aeon/MicroOS: transactional updates with Btrfs snapshots.
• Vanilla OS, Bazzite, Universal Blue: image-based systems focused on desktop or gaming.
• Advantages: rollback, fewer errors, background updates, security.
• Disadvantages: unfamiliar workflow for system packages, reboot needed after updates.

See also: DNF and RPM (Fedora, RHEL), Release models: fixed, LTS and rolling