[28][29] Other than the Linux kernel, key components that make up a distribution may include a display server (windowing system), a package manager, a bootloader and a Unix shell.

[g] When combined with Android, which is Linux-based and designed for smartphones, they have the largest installed base of all general-purpose operating systems.The Linux kernel was designed by Linus Torvalds, following the lack of a working kernel for GNU, a Unix-compatible operating system made entirely of free software that had been undergoing development since 1983 by Richard Stallman.

A working Unix system called Minix was later released but its license was not entirely free at the time[31] and it was made for an educative purpose.

The first entirely free Unix for personal computers, 386BSD, did not appear until 1992, by which time Torvalds had already built and publicly released the first version of the Linux kernel on the Internet.

[33] Linux distributions became popular in the 1990s and effectively made Unix technologies accessible to home users on personal computers whereas previously it had been confined to sophisticated workstations.

[44] The Chromebook, which runs the Linux kernel-based ChromeOS,[45][46] dominates the US K–12 education market and represents nearly 20 percent of sub-$300 notebook sales in the US.

This includes routers, automation controls, smart home devices, video game consoles, televisions (Samsung and LG smart TVs),[52][53][54] automobiles (Tesla, Audi, Mercedes-Benz, Hyundai, and Toyota),[55] and spacecraft (Falcon 9 rocket, Dragon crew capsule, and the Ingenuity Mars helicopter).

[56][57] The Unix operating system was conceived of and implemented in 1969, at AT&T's Bell Labs in the United States, by Ken Thompson, Dennis Ritchie, Douglas McIlroy, and Joe Ossanna.

[59] As a 1956 antitrust case forbade AT&T from entering the computer business,[60] AT&T provided the operating system's source code to anyone who asked.

Later, Sun Microsystems, founded as a spin-off of a student project at Stanford University, also began selling Unix-based desktop workstations in 1982.

While Sun workstations did not use commodity PC hardware, for which Linux was later originally developed, it represented the first successful commercial attempt at distributing a primarily single-user microcomputer that ran a Unix operating system.

[68] The course used a MicroVAX minicomputer running Ultrix, and one of the required texts was Operating Systems: Design and Implementation by Andrew S. Tanenbaum.

On July 3, 1991, to implement Unix system calls, Linus Torvalds attempted unsuccessfully to obtain a digital copy of the POSIX standards documentation with a request to the comp.os.minix newsgroup.

[72] Developers worked to integrate GNU components with the Linux kernel, creating a fully functional and free operating system.

Commercial use began when Dell and IBM, followed by Hewlett-Packard, started offering Linux support to escape Microsoft's monopoly in the desktop operating system market.

These third-party components comprise a vast body of work and may include both kernel modules and user applications and libraries.

Quality was maintained not by rigid standards or autocracy but by the naively simple strategy of releasing every week and getting feedback from hundreds of users within days, creating a sort of rapid Darwinian selection on the mutations introduced by developers.

For desktop systems, the default user interface is usually graphical, although the CLI is commonly available through terminal emulator windows or on a separate virtual console.

Distributions typically use a package manager such as apt, yum, zypper, pacman or portage to install, remove, and update all of a system's software from one central location.

[115][116] In many cities and regions, local associations known as Linux User Groups (LUGs) seek to promote their preferred distribution and by extension free software.

They hold meetings and provide free demonstrations, training, technical support, and operating system installation to new users.

[119][120] Although Linux distributions are generally available without charge, several large corporations sell, support, and contribute to the development of the components of the system and free software.

This used to be the norm in the computer industry, with operating systems such as CP/M, Apple DOS, and versions of the classic Mac OS before 7.6 freely copyable (but not modifiable).

Many programming languages have a cross-platform reference implementation that supports Linux, for example PHP, Perl, Ruby, Python, Java, Go, Rust and Haskell.

For example, regular expressions are supported in programs like grep and locate, the traditional Unix message transfer agent Sendmail contains its own Turing complete scripting system, and the advanced text editor GNU Emacs is built around a general purpose Lisp interpreter.

Guile Scheme acts as an extension language targeting the GNU system utilities, seeking to make the conventionally small, static, compiled C programs of Unix design rapidly and dynamically extensible via an elegant, functional high-level scripting system; many GNU programs can be compiled with optional Guile bindings to this end.

There are a number of Integrated development environments available including Anjuta, Code::Blocks, CodeLite, Eclipse, Geany, ActiveState Komodo, KDevelop, Lazarus, MonoDevelop, NetBeans, and Qt Creator, while the long-established editors Vim, nano and Emacs remain popular.

[133] The kernel also runs on architectures that were only ever intended to use a proprietary manufacturer-created operating system, such as Macintosh computers[134][135] (with PowerPC, Intel, and Apple silicon processors), PDAs, video game consoles, portable music players, and mobile phones.

[141] Analysts and proponents attribute the relative success of Linux to its security, reliability, low cost, and freedom from vendor lock-in.

[179] This distribution contained close to 283 million source lines of code, and the study estimated that it would have required about seventy three thousand man-years and cost US$10.2 billion[178] (in 2023 dollars) to develop by conventional means.