Introduction
Free and open-source software (FOSS) is software available under a license that gives users the right to use, share, modify, and distribute the software – modified or not – to everyone and provides the means to exercise those rights using the software's source code. FOSS is an inclusive umbrella term encompassing free software and open-source software. The rights guaranteed by FOSS originate from the "Four Essential Freedoms" of The Free Software Definition and the criteria of The Open Source Definition. All FOSS has publicly available source code, but not all source-available software is FOSS. FOSS is the opposite of proprietary software, which is licensed restrictively or has undisclosed source code.
The historical precursor to FOSS was the hobbyist and academic public domain software ecosystem of the 1960s to 1980s. Free and open-source operating systems such as Linux distributions and descendants of BSD are widely used, powering millions of servers, desktops, smartphones, and other devices. Free-software licenses and open-source licenses have been adopted by many software packages. Reasons for using FOSS include decreased software costs, increased security against malware, stability, privacy, opportunities for educational usage, and giving users more control over their own hardware.
The free software movement and the open-source software movement are online social movements behind widespread production, adoption and promotion of FOSS, with the former preferring to use the equivalent term free/libre and open-source software. FOSS is supported by a loosely associated movement of multiple organizations, foundations, communities and individuals who share basic philosophical perspectives and collaborate practically, but may diverge in detail questions. (More about free and open-source software...)
Terminology
Alternative terms for free software, such as OSS, FOSS, and FLOSS, have been a recurring issue among free and open-source software users from the late 1990s onwards. These terms share almost identical licence criteria and development practices.
In 1983 Richard Stallman launched the free software movement and founded the Free Software Foundation to promote the movement and to publish its own definition. Others have published alternative definitions of free software, notably the Debian Free Software Guidelines. In 1998, Bruce Perens and Eric S. Raymond began a campaign to market open-source software and founded the Open Source Initiative, which espoused different goals and a different philosophy from Stallman's. (Full article...)
Selected article
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DragonFly BSD is a free and open-source Unix-like operating system forked from FreeBSD 4.8. Matthew Dillon, an Amiga developer in the late 1980s and early 1990s and FreeBSD developer between 1994 and 2003, began working on DragonFly BSD in June 2003 and announced it on the FreeBSD mailing lists on 16 July 2003.
Dillon started DragonFly in the belief that the techniques adopted for threading and symmetric multiprocessing in FreeBSD 5 would lead to poor performance and maintenance problems. He sought to correct these anticipated problems within the FreeBSD project. Due to conflicts with other FreeBSD developers over the implementation of his ideas, his ability to directly change the codebase was eventually revoked. Despite this, the DragonFly BSD and FreeBSD projects still work together, sharing bug fixes, driver updates, and other improvements. Dillon named the project after photographing a dragonfly in his yard, while he was still working on FreeBSD.
Intended as the logical continuation of the FreeBSD 4.x series, DragonFly has diverged significantly from FreeBSD, implementing lightweight kernel threads (LWKT), an in-kernel message passing system, and the HAMMER file system. Many design concepts were influenced by AmigaOS. (Full article...) -
Terrence Andrew Davis (December 15, 1969 – August 11, 2018) was an American electrical engineer, computer programmer, and outsider artist best known for creating and designing TempleOS, a public domain operating system. In 1996, Davis began experiencing regular manic episodes, some of which led to hospitalization. Initially diagnosed with bipolar disorder, he was later declared to have schizophrenia. Eight months before his death, he struggled with periods of homelessness. His fans brought him supplies, but Davis refused their offers of housing. In August 2018, he was struck by a train and died at the age of 48. (Full article...) -
Debian (/ˈdɛbiən/) is a Linux distribution developed by the Debian Project, established by Ian Murdock in August 1993.
Debian is developed openly by a team of volunteers guided by the Debian Project Leader and three foundation documents: the Debian Social Contract, the Debian Constitution, and the Debian Free Software Guidelines.
As of January 2026, the Debian community has over 1,400 active contributors, who maintain, document, and support more than 94,000 free packages.
The Free Software Foundation sponsored the project from November 1994 to November 1995, ending their sponsorship over technical disagreements and Debian's inclusion of optional non-free software and firmware repositories. In response, members of the Debian Project founded the non-profit organization Software in the Public Interest in 1997 to enable the project to accept donations and provide legal backing for its trademarks.
Debian is the second-oldest Linux distribution still in active development; only Slackware is older. Debian forms the basis of many other Linux distributions. (Full article...) -
Tux Racer is a 2000 open-source winter sports racing video game starring the Linux mascot, Tux the penguin. It was originally developed by Jasmin Patry as a computer graphics project at the University of Waterloo. Later on, Patry and the newly founded Sunspire Studios, composed of several former students of the university, expanded it. In the game, the player controls Tux as he slides down a course of snow and ice collecting herrings.
Tux Racer was officially downloaded over one million times as of 2001. It also was well received, often being acclaimed for the graphics, fast-paced gameplay, and replayability, and was a fan favorite among Linux users and the free software community. The game's popularity secured the development of a proprietized release that included enhanced graphics and multiplayer, and it also became the first GPL-licensed game to receive an arcade adaptation. It is the only product that Sunspire Studios developed and released, after which the company liquidated. (Full article...) -
Rust is a general-purpose programming language. It is noted for its emphasis on performance, type safety, concurrency, and memory safety.
Rust supports multiple programming paradigms. It was influenced by ideas from functional programming, including immutability, higher-order functions, algebraic data types, and pattern matching. It also supports object-oriented programming via structs, enums, traits, and methods. Rust is noted for enforcing memory safety (i.e., that all references point to valid memory) without a conventional garbage collector; instead, memory safety errors and data races are prevented by the "borrow checker", which tracks the object lifetime of references at compile time.
Software developer Graydon Hoare created Rust in 2006 while working at Mozilla, which officially sponsored the project in 2009. The first stable release, Rust 1.0, was published in May 2015. Following a layoff of Mozilla employees in August 2020, four other companies joined Mozilla in sponsoring Rust through the creation of the Rust Foundation in February 2021.
Rust has been adopted by many software projects, especially web services and system software. It has been studied academically and has a growing community of developers. (Full article...) -
Popular open source licenses include the Apache License, the MIT License, the GNU General Public License (GPL), the BSD Licenses, the GNU Lesser General Public License (LGPL) and the Mozilla Public License (MPL).
Open-source licenses are software licenses that allow content to be used, modified, and shared. They facilitate free and open-source software (FOSS) development. Intellectual property (IP) laws restrict the modification and sharing of creative works. Free and open-source licenses use these existing legal structures for an inverse purpose. They grant the recipient the rights to use the software, examine the source code, modify it, and distribute the modifications. These criteria are outlined in the Open Source Definition.
After 1980, the United States began to treat software as a literary work covered by copyright law. Richard Stallman founded the free software movement in response to the rise of proprietary software. The term "open source" was used by the Open Source Initiative (OSI), founded by free-software developers Bruce Perens and Eric S. Raymond. "Open source" emphasizes the strengths of the open development model rather than software freedoms. While the goals behind the terms are different, open-source licenses and free-software licenses describe the same type of licenses.
The two main categories of open-source licenses are permissive and copyleft. Both grant permission to change and distribute software. Typically, they require attribution and disclaim liability. Permissive licenses come from academia. Copyleft licenses come from the free software movement. Copyleft licenses require derivative works to be distributed with the source code and under a similar license. Since the mid-2000s, courts in multiple countries have upheld the terms of both types of license. Software developers have filed cases as copyright infringement and as breaches of contract. (Full article...) -
Dolphin is a free and open-source video game console emulator of the GameCube, Wii and Triforce arcade system that runs on Windows, Linux, macOS, and Android.
It had its inaugural release in 2003 as freeware for Windows. Dolphin was the first GameCube emulator that could successfully run commercial games. After troubled development in the first years, Dolphin became free and open-source software and subsequently gained support for Wii emulation. Soon after, the emulator was ported to Linux and macOS. As mobile hardware became more powerful over the years, running Dolphin on Android became a viable option.
Dolphin has been well received in the IT and video gaming media for its high compatibility, steady development progress, the number of available features, and the ability to play games with graphical improvements over the original platforms. (Full article...) -
Brave is a free and open-source web browser which was first released in 2016. It is developed by US-based Brave Software, Inc. and based on the Chromium web browser. Brave is marketed as a privacy-focused web browser and includes features such as built-in advertisement blocking, protections against browser fingerprinting and a private browsing mode that integrates the Tor anonymity network. Brave also incorporates its own advertising through a rewards system based on cryptocurrency, which allows users to earn Basic Attention Tokens (BAT) by opting-in to view ads served through its ad network. While Brave has been praised for its privacy protections and features, it has faced criticism over early plans to replace publisher's ads with its own and missteps surrounding its handling of affiliate links and privacy vulnerabilities in its private browsing mode. (Full article...) -
Pocket Casts is a podcast streaming service originally launched in 2011 for iOS and Android. The app allows for searching, downloading and subscribing to podcasts and syncs across devices. Pocket Casts was developed by Russell Ivanovic and Philip Simpson under the Australian independent development team Shifty Jelly. In 2018, the app was acquired by a group of public radio organisations including National Public Radio before being sold to WordPress.com owner Automattic in 2021.
With initial development efforts focusing on Android, Pocket Casts for iOS and Android was made free and open source in 2022 and received its latest major release 8.0 in 2025. It was also launched for the web, macOS, and Windows, and integrated to car head units, smart speakers, and smartwatch operating systems. Initially requiring a one-time fee, Pocket Casts switched to a freemium model in 2019, adding a subscription plan with more features. Commentators have directed praise to the array of features and the interface's simplicity. In 2020, a request by the Cyberspace Administration of China led to the removal of Pocket Casts from Apple's App Store in China. (Full article...) -
GNOME Web, called Epiphany until 2012 and still known by that code name, is a free and open-source web browser based on the GTK port of Apple's WebKit rendering engine, called WebKitGTK. It is developed by the GNOME project for Unix-like systems. It is the default and official web browser of GNOME, and part of the GNOME Core Applications.
GNOME Web is the default web browser on elementary OS, Bodhi Linux version 5 and PureOS GNOME Edition. (Full article...) -
The Ur-Quan Masters is a 2002 open-source fangame modification, based on the action-adventure science fiction game Star Control II. The original game was released for PCs in 1992 and ported to the 3DO console in 1994. It has been frequently mentioned among the best games of all time, with additional praise for its writing, world design, character design, and music.
After the Star Control II copyrights reverted to creators Paul Reiche III and Fred Ford, they licensed their content to their fan community under the GNU General Public License, to keep their series in the public eye. The open-source development team remade the 3DO version as a port to modern operating systems, and allowed fan-made modifications to add improvements absent in the original release. Released under the title The Ur-Quan Masters (the subtitle of the original game), the modified remake has since been downloaded nearly two million times, earning critical reception as one of the best free games available, with additional praise for a high-definition graphics fan modification. (Full article...) -
Leafpad is a free and open-source graphical text editor for Linux, Berkeley Software Distribution (BSD), and Maemo that is similar to the Microsoft Windows program Notepad. Created with the focus of being a lightweight text editor with minimal dependencies, it is designed to be simple-to-use and easy-to-compile.
Leafpad has a small install size compared to other graphical text editors and has minimal features such as codeset options, undo/redo, and the ability to choose fonts. Leafpad is the default text editor for the LXDE lightweight desktop environment, and thus Leafpad is found on Linux distributions that use LXDE as their desktop environment such as Raspberry Pi OS, as well as on some embedded systems. The program has been forked into Mousepad and l3afpad, and parts of Leafpad's code have been used in other text editors. Leafpad is released under the GNU General Public License (GPL) version 2. (Full article...) -
DOSBox is a free and open-source MS-DOS emulator. It supports running programs – primarily video games – that are otherwise inaccessible since hardware for running a compatible disk operating system (DOS) is obsolete and generally unavailable today. It was first released in 2002, when DOS technology was becoming obsolete. Its adoption for running DOS games is relatively widespread, partly because of its use in commercial re-releases of games. (Full article...) -
Plan 9 from Bell Labs is an operating system designed by the Computing Science Research Center (CSRC) at Bell Labs in the mid-1980s, built on the UNIX concepts first developed there in the late 1960s. Since 2000, Plan 9 has been free and open-source. The final official release was in early 2015.
Under Plan 9, UNIX's everything is a file metaphor is extended via a pervasive network-centric (distributed) filesystem, and the cursor-addressed, terminal-based I/O at the heart of UNIX is replaced by a windowing system and graphical user interface without cursor addressing (although rc, the Plan 9 shell, is text-based). Plan 9 also introduced capability-based security and a log-structured file system called Fossil that provides snapshotting and versioned file histories.
The name Plan 9 from Bell Labs is a reference to the Ed Wood 1957 cult science fiction Z-movie Plan 9 from Outer Space. The system continues to be used and developed by operating system researchers and hobbyists. (Full article...)
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Did you know?
- ... that Terry Davis created TempleOS, a Bible-themed operating system that had more than 120,000 lines of code? (2025-03-20)
- ... that the browser extension AdNauseam blocks and clicks on advertisements at the same time? (2025-01-06)
- ... that Riley Testut developed AltStore because he wanted to publish his emulator Delta? (2024-06-01)
- ... that you can keep a snowflake in a browser tab? (2022-11-08)
- ... that Kotaku revised an article about Nintendo Switch emulation after Nintendo complained that the previous version encouraged piracy? (2022-10-17)
- ... that Vegeta is used to attack HTTP-based applications? (2022-09-11)
- ... that Leafpad is a text editor for Linux that is comparable to Notepad for Windows? (2022-08-30)
Transcluding 7 of 24 total
Get involved
Wikipedia is an encyclopedia written entirely by volunteers. If you wish to contribute to our articles, feel free to join the free and open-source task force. To find a place to start, you can expand a stub or improve existing articles. To pick an existing article, you could choose from the list of most-viewed FOSS articles or a vital article about free and open-source software. The vital articles are listed below with their current content assessment rating:
Android (operating system)
Tim Berners-Lee- Copyright
- Donald Knuth
- Linux
- Open-source software
- Patent
- Linus Torvalds
- Bell Labs
- Berkeley Open Infrastructure for Network Computing
- Bitcoin
- Copyleft
Debian- Digital rights management
- Brendan Eich
- Emacs
- Ext4
- Firefox
- Free content
- Free-culture movement
- Free Software Foundation
- GIMP
- GNU Project
- GitHub
- GTK
- Leslie Lamport
- Lawrence Lessig
- LibreOffice
- Lua
Yukihiro Matsumoto- Bram Moolenaar
- MySQL
- Ogg
- Open source
- OpenGL
- PHP
- Perl
- Python (programming language)
- R (programming language)
- Guido van Rossum
- Ruby (programming language)
- SPICE
- Richard Stallman
- Swift (programming language)
- TeX
- Tor (network)
- VLC media player
- Vim (text editor)
- VirtualBox
- Wine (software)
- X Window System
Related portals
Topics
| General | |||
|---|---|---|---|
| Software packages | |||
| Community | |||
| Organisations | |||
| Licenses |
| ||
| Challenges | |||
| Related topics | |||
- Impediments and challenges
- Digital Millennium Copyright Act · Digital rights management · Tivoization · Software patents and free software · Trusted Computing · Proprietary software · SCO-Linux controversies · Binary blobs
- Adoption issues
- OpenDocument format · Vendor lock-in · GLX · Free standards · Free software adoption cases
- About licences
- Free software licences · Copyleft · List of FSF-approved software licenses
- Common licences
- GNU General Public License · GNU Lesser General Public License · GNU Affero General Public License · IBM Public License · Mozilla Public License · Permissive free software licences
- History
- ...of free software · Free software movement · Timeline of free and open-source software
- Groupings of software
- Comparison of free software for audio · List of open-source video games
- Naming issues
- GNU/Linux naming controversy · Alternative terms for free software · Naming conflict between Debian and Mozilla
Wikimedia
The following Wikimedia Foundation sister projects provide more on this subject:
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Commons
Free media repository -
Wikibooks
Free textbooks and manuals -
Wikidata
Free knowledge base -
Wikinews
Free-content news -
Wikiquote
Collection of quotations -
Wikisource
Free-content library -
Wikiversity
Free learning tools -
Wiktionary
Dictionary and thesaurus
Categories
Types of software
The following types are the selected sub-categories of Category:Free software:
- Antivirus software
- Application servers
- Astronomy software
- Audio software
- Backup software
- BitTorrent clients
- Business software
- Compilers and interpreters
- Computer-aided design software
- Content management systems
- Cross-platform software
- Data compression software
- Database management systems
- Desktop environments
- Development toolkits and libraries
- Educational software
- Email software
- File managers
- File transfer software
- Games
- GIS software
- 2D graphics software
- 3D graphics software
- Groupware
- HTML editors
- Image galleries
- Instant messengers
- Internet forum software
- IRC clients
- Learning support software
- Mathematics software
- Media players
- Multimedia codecs, containers, and splitters
- Network management software
- Note-taking software
- Office suites
- Operating systems
- Optical disc authoring software
- PDF software
- Personal information managers
- Project management software
- Science software
- Search engine software
- Special purpose file systems
- Spreadsheets
- System software
- Television software
- TeX software
- Text editors
- Usenet clients
- Version control software
- Video software
- VoIP software
- Web browsers
- Windowing systems
- Word processors
- X window managers
People, projects, and groupings
- Apache Software Foundation projects
- Free software programmers
- Free and open-source software organizations
- Members of the Free Software Foundation board of directors
- Free Software Foundation
- GNU project and GNU project software
- Free software companies
Non-software materials
- Free and open-source software licenses
- Free software websites
- Free-software awards
- Free-software events
- Copyleft
- Free software culture and documents
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