Linux is a family of free and open-source software operating systems built around the Linux kernel.
GNU/LinuxLinuxLinLinux operating systemLinux-basedLinux kernelLinux desktopdesktop LinuxLinux OSLinux on the desktop

Linux kernel

LinuxkernelLinux kernel
Linux is a family of free and open-source software operating systems built around the Linux kernel. The defining component of a Linux distribution is the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds.
The Linux family of operating systems is based on this kernel and deployed on both traditional computer systems such as personal computers and servers, usually in the form of Linux distributions, and on various embedded devices such as routers, wireless access points, PBXes, set-top boxes, FTA receivers, smart TVs, PVRs, and NAS appliances.

Linus Torvalds

Just for FunDavid DiamondLinus
The defining component of a Linux distribution is the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds.
Linus Benedict Torvalds (born December 28, 1969) is a Finnish–American software engineer who is the creator, and historically, the principal developer of the Linux kernel, which became the kernel for operating systems such as the Linux operating system, Android, and Chrome OS.

Chromebook

ChromebooksGoogle Chromebookschromebook
The Chromebook, which runs the Linux kernel-based Chrome OS, dominates the US K–12 education market and represents nearly 20% of the sub-$300 notebook sales in the US. Linux also runs on embedded systems, i.e. devices whose operating system is typically built into the firmware and is highly tailored to the system.
A Chromebook is a laptop or tablet running the Linux-based Chrome OS as its operating system.

Supercomputer

supercomputerhigh-performance computingsupercomputing
Linux is also the leading operating system on servers and other big iron systems such as mainframe computers, and the only OS used on TOP500 supercomputers (since November 2017, having before gradually eliminated all competitors).
As of November 2017, all of the world's fastest 500 supercomputers run Linux-based operating systems.

Personal computer

PCpersonal computerPCs
Linux was originally developed for personal computers based on the Intel x86 architecture, but has since been ported to more platforms than any other operating system.
These include Apple's macOS and free and open-source Unix-like operating systems such as Linux.

Operating system

operating systemoperating systemsOS
Linux is a family of free and open-source software operating systems built around the Linux kernel. The Chromebook, which runs the Linux kernel-based Chrome OS, dominates the US K–12 education market and represents nearly 20% of the sub-$300 notebook sales in the US. Linux also runs on embedded systems, i.e. devices whose operating system is typically built into the firmware and is highly tailored to the system. Because of the dominance of the Linux kernel-based Android OS on smartphones, Linux has the largest installed base of all general-purpose operating systems.
macOS by Apple Inc. is in second place (13.23%), and the varieties of Linux are collectively in third place (1.57%).

Fedora (operating system)

FedoraFedora CoreFedora 9
Some of the most popular and mainstream Linux distributions are Arch Linux, CentOS, Debian, Raspbian, Fedora, Gentoo Linux, Linux Mint, Mageia, openSUSE and Ubuntu, together with commercial distributions such as Red Hat Enterprise Linux and SUSE Linux Enterprise Server.
Fedora is a Linux distribution developed by the community-supported Fedora Project and sponsored by Red Hat.

OpenSUSE

openSUSEopenSUSE TumbleweedSUSE
Some of the most popular and mainstream Linux distributions are Arch Linux, CentOS, Debian, Raspbian, Fedora, Gentoo Linux, Linux Mint, Mageia, openSUSE and Ubuntu, together with commercial distributions such as Red Hat Enterprise Linux and SUSE Linux Enterprise Server.
openSUSE, formerly SUSE Linux and SuSE Linux Professional, is a Linux-based project and distribution sponsored by SUSE Linux GmbH and other companies.

Free and open-source software

free and open-sourcefree and open-source softwarefree and open source software
Linux is a family of free and open-source software operating systems built around the Linux kernel.
"Free and Open-source" (FOSS) operating systems such as Linux and descendants of BSD are widely utilized today, powering millions of servers, desktops, smartphones (e.g. Android), and other devices.

GNOME

GNOMEGNOME desktop environmentGNOME 2
Desktop Linux distributions include a windowing system, such as X11, Mir or a Wayland implementation, and an accompanying desktop environment such as GNOME or KDE Plasma; some distributions may also include a less resource-intensive desktop, such as LXDE or Xfce.
GNOME is a desktop environment composed of free and open-source software that runs on Linux and BSD derivatives.

LAMP (software bundle)

LAMPLAMP stackSAMP
Distributions intended to run on servers may omit all graphical environments from the standard install, and instead include other software to set up and operate a solution stack such as LAMP.
LAMP is an archetypal model of web service stacks, named as an acronym of the names of its original four open-source components: the GNU/Linux operating system, the Apache HTTP Server, the MySQL relational database management system (RDBMS), and the PHP programming language.

Xfce

XfcexfwmMousepad
Desktop Linux distributions include a windowing system, such as X11, Mir or a Wayland implementation, and an accompanying desktop environment such as GNOME or KDE Plasma; some distributions may also include a less resource-intensive desktop, such as LXDE or Xfce.
Xfce (pronounced as four individual letters) is a free and open-source desktop environment for Unix and Unix-like operating systems, such as Linux, Solaris, and BSD.

Mir (software)

MirMir display serverwidespread objection from the open source desktop community
Desktop Linux distributions include a windowing system, such as X11, Mir or a Wayland implementation, and an accompanying desktop environment such as GNOME or KDE Plasma; some distributions may also include a less resource-intensive desktop, such as LXDE or Xfce.
Mir is a computer display server and, recently, a Wayland compositor for the Linux operating system that is under development by Canonical Ltd. It was planned to replace the currently used X Window System for Ubuntu, however the plan changed and Mutter was adopted as part of GNOME Shell.

GNU

GNUGNU ProjectGNU operating system
The Free Software Foundation uses the name GNU/Linux to refer to the operating system family, as well as specific distributions, to emphasize that most Linux distributions are not just the Linux kernel, and that they have in common not only the kernel, but also numerous utilities and libraries, a large proportion of which are from the GNU project.
The combination of GNU software and the Linux kernel is commonly known as Linux (or less frequently GNU/Linux; see GNU/Linux naming controversy).

Package manager

package managerpackage management systemsoftware packages
Typically, Linux is packaged in a form known as a Linux distribution (or distro for short) for both desktop and server use.
This can be particularly useful for large enterprises whose operating systems are based on Linux and other Unix-like systems, typically consisting of hundreds or even tens of thousands of distinct software packages.

FreeBSD

FreeBSD*BSDLinux emulation
Although not released until 1992, due to legal complications, development of 386BSD, from which NetBSD, OpenBSD and FreeBSD descended, predated that of Linux.
FreeBSD has similarities with Linux, with two major differences in scope and licensing: FreeBSD maintains a complete operating system, i.e. the project delivers kernel, device drivers, userland utilities, and documentation, as opposed to Linux only delivering a kernel and drivers, and relying on third-parties for system software; and FreeBSD source code is generally released under a permissive BSD license, as opposed to the copyleft GPL used by Linux.

Wayland (display server protocol)

WaylandWestonlibinput
Desktop Linux distributions include a windowing system, such as X11, Mir or a Wayland implementation, and an accompanying desktop environment such as GNOME or KDE Plasma; some distributions may also include a less resource-intensive desktop, such as LXDE or Xfce.
Wayland is developed by a group of volunteers initially led by Kristian Høgsberg as a free and open community-driven project with the aim of replacing the X Window System with a modern, simpler windowing system in Linux and other Unix-like operating systems.

Android (operating system)

AndroidAndroid operating systemAndroid OS
Because of the dominance of the Linux kernel-based Android OS on smartphones, Linux has the largest installed base of all general-purpose operating systems.
Within a year, the Open Handset Alliance faced two other open source competitors, the Symbian Foundation and the LiMo Foundation, the latter also developing a Linux-based mobile operating system like Google.

Mainframe computer

mainframemainframe computermainframes
Linux is also the leading operating system on servers and other big iron systems such as mainframe computers, and the only OS used on TOP500 supercomputers (since November 2017, having before gradually eliminated all competitors).
In addition, mainframes are more secure than other computer types: the NIST vulnerabilities database, US-CERT, rates traditional mainframes such as IBM Z (previously called z Systems, System z and zSeries), Unisys Dorado and Unisys Libra as among the most secure with vulnerabilities in the low single digits as compared with thousands for Windows, UNIX, and Linux.

Systemd

systemdjournaldeudev
Projects such as Upstart and systemd aim for a faster boot time; the Wayland and Mir projects aim at replacing X11 while enhancing desktop performance, security and appearance.
Systemd (stylized as systemd) is a suite of software that provides fundamental building blocks for a Linux operating system.

Usage share of operating systems

over 90% market shareusage share of operating systemsUsecond most widely used desktop OS
Because of the dominance of the Linux kernel-based Android OS on smartphones, Linux has the largest installed base of all general-purpose operating systems.
Most desktop and laptop computers still use Microsoft Windows, while all TOP500 supercomputers use Linux.

Porting

portedportports
Linux was originally developed for personal computers based on the Intel x86 architecture, but has since been ported to more platforms than any other operating system.
In that same market, the choice of operating systems has effectively been reduced to three: Microsoft Windows, macOS, and Linux.

BusyBox

busyboxbusybox-w32busybox vi
It runs in a variety of POSIX environments such as Linux, Android, and FreeBSD, although many of the tools it provides are designed to work with interfaces provided by the Linux kernel.

Booting

bootloaderbootbooting
The boot manager lets a user choose which operating system to run and set more complex parameters for it. The firmware or the boot manager then loads the boot loader into the memory and runs it. This piece of software is able to place an operating system kernel like Windows or Linux into the computers main memory and run it. Afterwards, the kernel runs so-called user space software – well known is the graphical user interface (GUI), which lets the user log in to the computer or run some other applications.

Bash (Unix shell)

BashBash shellbash scripts
The project also develops a popular CLI shell.
First released in 1989, it has been distributed widely as the default login shell for most Linux distributions and Apple's macOS (formerly OS X). A version is also available for Windows 10.