Linux

Linux is a family of free-and-open-source Unix-like operating systems based on the Linux kernel. The kernel was first released on 17 September 1991 by Linus Torvalds. These operating systems are often called "distros," or distributions. A distro includes the kernel and other software and libraries made by others, such as GNU, Red Hat, and X.Org, to create a full operating system. However, not all Linux-based systems are called distros. For example, Android is based on Linux but is not usually called a distro.

There are thousands of different Linux distributions. Some popular ones are 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 include the word "Linux" in their name. The Free Software Foundation prefers the name "GNU/Linux" to show the importance of GNU software in these systems.

Linux shows how people can work together to create free and open-source software. The Linux kernel is one of the largest open source projects ever. It was first made for x86-based personal computers but now runs on many 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 include Android, which uses a Linux-based kernel and is made for smartphones, Linux and Android together have the most 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. Its goal was to create 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, called 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. This 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 grew and changed over time instead of being designed all at once. Linus Torvalds thinks that while Unix was a good start, Linux became special in its own way. Eric S. Raymond says Linux is strong because many people worked on it together over the Internet, sharing ideas and fixing problems fast.

A Linux system is a type of operating system that uses ideas from older systems called Unix. It uses something called a monolithic kernel to control programs, manage networks, and work with devices. There are also many extra pieces of software that help users and programs.

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

User interface

You can use a Linux system in different ways. Some systems let 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, so it can work with many 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 main 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 used by many people.

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

Community

Linux communities help make it better. 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 devices, from phones to big computers. It runs on different computer designs, like phones with ARM chips and large IBM Z machines. There are special versions of Linux for older or less common computer designs.

Linux is good with older devices because it keeps drivers for a long time. People work together to improve Linux for many types of hardware. Over time, Linux has gotten better with new devices, so most things you buy will work well with it.

Security

Main articles: Computer security and Open-source software security

Many people think Linux gets safer because lots of people look at the software often. This idea is called "Linus's law." Linux is used on many computers worldwide. Groups like the Open Source Security Foundation and the Linux Foundation work to keep Linux safe for everyone.