NixOS is a unique Linux distribution that uses a declarative configuration model. This means that users define their system's configuration in a single file, allowing for easy reproducibility and management of software packages. The package manager, Nix, ensures that software installations are isolated, preventing conflicts between different applications. One of the key features of NixOS is its ability to roll back system changes. If an update or configuration change causes issues, users can revert to a previous state effortlessly. This makes NixOS particularly appealing for developers and system administrators who require stability and reliability in their environments.