Textbook of Linux

Also known as: distro

A distribution (or "distro") is a packaged, ready-to-install Linux-based operating system. Because the Linux kernel alone is not usable—you also need a C library, a shell, init, utilities, and some way to install and update software—distributors bundle all of these into a coherent whole and release it as a single product. The first widely used distributions appeared in 1992–93: Softlanding Linux System (SLS), Slackware, and Debian.

Distributions differ in philosophy and audience. Debian prizes stability and a strict free-software policy; Ubuntu, built on Debian, emphasises desktop usability and predictable releases; Fedora chases the leading edge of upstream software and feeds into enterprise Red Hat Enterprise Linux; Arch gives users a minimal rolling-release base to build on; Alpine is tiny and security-focused, popular for containers; NixOS models the entire system as a reproducible configuration. Each chooses its own package format, default init system, release cadence, and defaults.

Distributions matter because they determine the day-to-day experience: which package manager you use, which versions of software you get, what documentation is available, and how you receive security updates. Choosing a distribution is often the first decision a new Linux user makes, though in practice most distributions are more alike than different once you reach the shell.