Linux

Linux is a family of free-and-open-source Unix-like operating systems based on the Linux kernel, which was first released on 17 September 1991 by Linus Torvalds. Some of these operating systems are usually packaged as a distribution, or "distro," which includes the kernel along with supporting software and libraries developed by others, such as GNU, Red Hat, and X.Org, to create a complete operating system. Not all Linux-based systems are called distros, though; for example, Android is based on Linux but is not typically called a distro.

There are thousands of different Linux distributions. Popular ones include Debian, Fedora Linux, Linux Mint, Arch Linux, and Ubuntu. Commercial versions include Red Hat Enterprise Linux, SUSE Linux Enterprise, and ChromeOS. Linux distributions are often used on servers, and many use the word "Linux" in their name. The Free Software Foundation prefers the name "GNU/Linux" to highlight the important role of GNU software in these systems.

Linux is a great example of how people can work together to create free and open-source software. The Linux kernel is considered one of the largest open source projects ever. It was first made for x86-based personal computers but has since been adapted to run on many different types of devices, from PCs and workstations to mainframes and small embedded systems. Today, Linux is the main operating system for servers and is used on all of the world's 500 fastest supercomputers. When you add Android, which uses a Linux-based kernel and is made for smartphones, Linux and Android together have the largest number of users of any general-purpose operating system.

Overview

The Linux kernel was created by Linus Torvalds because there was no working kernel for GNU, a Unix-like operating system made from free software. GNU had been developed since 1983 by the GNU Project, led by Richard Stallman. Later, a Unix system called Minix was released, but its license was not fully free. The first fully free Unix for personal computers, 386BSD, came out in 1992, after Torvalds had already released the first version of the Linux kernel on the Internet. Linux avoided legal issues because it was a new creation, not using any Unix code.

Linux became popular in the 1990s, bringing Unix technology to home users. Desktop versions of Linux include a way to create windows and graphics, like KDE Plasma, GNOME, or Xfce. Server versions might not have graphics at all. Anyone can use, change, and share Linux's source code under its licenses, such as the GNU General Public License. Because of Android, which uses Linux, Linux has the most users of any operating system. It is used on many desktop computers, servers, and even in smart home devices, cars, and spacecraft.

History

The Unix operating system began in 1969 at Bell Labs in the United States. It was written in a special computer language and became very popular.

Later, a project called the GNU Project started in 1983 with the goal of creating a complete system using free software. Many important parts of an operating system were finished, but some pieces were still missing.

Linus Torvalds, principal author of the Linux kernel

In 1991, a student named Linus Torvalds began working on his own operating system kernel, which became known as Linux. He started this project while attending the University of Helsinki. Torvalds developed Linux on a small computer system and shared it with others.

The Linux kernel is licensed under the GNU General Public License, which means anyone can use, change, and share the software freely. Many companies and individuals have helped develop Linux, adding new features and improvements over the years.

Today, Linux is used in many places, from small devices to powerful computers. It is especially popular for servers and smartphones, where Android, a type of Linux, is the most used operating system.

Usage

Many studies look at how often people use Linux and how well it works. Linux is becoming more popular, and experts think the amount of money related to Linux will grow a lot by 2027. People like Linux because it is safe, reliable, cheap, and doesn’t make you stick with one company.

Linux is used on many types of computers. In October 2024, about 4.3% of desktop computers used Linux. Most desktop computers use Microsoft Windows. On websites, Linux is very common. Most of the biggest websites run on Linux.

Linux is also used on many phones. Android, which uses Linux, is the most popular operating system for smartphones and tablets. In April 2023, most phones using the internet were Android phones.

Linux is also used in making movies. Many big movie studios use Linux to create their films.

Linux is used by many governments around the world. Some countries have made their own versions of Linux for their schools and offices. In April 2026, France planned to start using Linux on many of its computers instead of Windows.

Design

The Linux kernel wasn't designed in the usual way; it grew and changed over time. Linus Torvalds thinks that while Unix was a good starting point, Linux developed with many changes that made it unique. Eric S. Raymond believes Linux's strength comes from how it was created — many people worked on it together over the Internet, sharing ideas and fixing problems quickly.

A Linux system is a type of operating system that shares ideas from older systems called Unix. It uses something called a monolithic kernel, which handles many important tasks like controlling programs, managing networks, and dealing with devices. There are also many extra pieces of software that work with the kernel, like tools for users and programs to make things easier.

When you start a Linux system, it uses a special program called a bootloader to get everything ready. Then, it starts other programs that help run the system. There are also many libraries — collections of code that programs can use — and basic tools that work on Linux. For graphics, Linux can use different ways to show pictures and windows on the screen.

User interface

The way you use a Linux system can be different. Some systems use a text-based interface where you type commands, while most desktop systems have a graphical interface with pictures and windows that you can click on. Popular graphical interfaces include GNOME, KDE, and others. These interfaces often use something called the X Window System to manage windows and graphics. Some newer systems are starting to use Wayland instead.

Video input infrastructure

Main article: Video4Linux

Linux has special ways to work with cameras and other video devices. It uses two main systems to handle video and radio inputs, making it work with many different types of hardware.

Various layers within Linux, also showing separation between the userland and kernel space
Hardware (CPU, main memory, data storage devices, etc.)
User mode	User applications	bash, LibreOffice, GIMP, Blender, 0 A.D., Mozilla Firefox, ...
	System components	init daemon: OpenRC, runit, systemd, ...	System daemons: polkitd, smbd, sshd, udevd, ...	Windowing system: X11, Wayland, SurfaceFlinger (Android)	Graphics: Mesa, AMD Catalyst, ...	Other libraries: GTK, Qt, EFL, SDL, SFML, FLTK, GNUstep, ...
	C standard library	fopen, execv, malloc, memcpy, localtime, pthread_create, ... (up to 2000 subroutines) glibc aims to be fast, musl aims to be lightweight, uClibc targets embedded systems, bionic was written for Android, etc. All aim to be POSIX/SUS-compatible.
Kernel mode	Linux kernel	stat, splice, dup, read, open, ioctl, write, mmap, close, exit, etc. (about 380 system calls) The Linux kernel System Call Interface (SCI), aims to be POSIX/SUS-compatible
		Process scheduling subsystem	IPC subsystem	Memory management subsystem	Virtual files subsystem	Networking subsystem
		Other components: ALSA, DRI, evdev, klibc, LVM, device mapper, Linux Network Scheduler, Netfilter Linux Security Modules: SELinux, TOMOYO, AppArmor, Smack

Development

Linux is special because its core part, called the kernel, and many other pieces are free and open-source software. This means anyone can see, change, and share the code. Many other operating systems are not like this, but Linux is widely used.

Linux works well with other systems and follows many important standards. Developers make packages of software that users can add to their Linux system to customize it. These packages are managed by tools that help install, remove, and update software easily.

Community

Linux communities help drive its development. Some groups, like Debian, work entirely as volunteers. Others, like Red Hat, have both community and commercial versions of their software.

Local groups called Linux User Groups (LUGs) support users by holding meetings and offering help. Online, many forums and chatrooms exist for Linux users to share ideas and solve problems. Companies also support Linux development, sometimes by paying programmers to work on it.

Photo of GNUCash accounting and bookkeeping program

Programming on Linux

Graphics and graphics design

Common graphic design tools on Linux include GIMP for image editing, Inkscape for vector graphics, Krita for painting, DaVinci Resolve for video editing, and Scribus for page layout.

Hardware support

The Linux kernel works on many types of devices, from phones to very large computers. It can run on many different kinds of computer designs, such as phones using ARM chips and big IBM Z machines. There are special versions of Linux for older or less common computer designs.

Linux is known for working well with older devices by keeping drivers available for a long time. Groups and meetings focus on improving Linux support for many types of hardware. Over time, Linux has gotten better at working with new devices, so most things you buy will likely work well with it.

Security

Main articles: Computer security and Open-source software security

Many people believe that Linux becomes safer over time because many people check the software regularly. This idea is known as "Linus's law." Linux is often used on computers around the world. Groups like the Open Source Security Foundation and the Linux Foundation work hard to keep Linux safe for everyone.