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Free software (or libre software) is computer software distributed under terms that allow users to run the software for any purpose as well as to study, change, and distribute it and any adapted versions. Free software is a matter of
liberty Broadly speaking, liberty is the ability to do as one pleases, or a right or immunity enjoyed by prescription or by grant (i.e. privilege). It is a synonym for the word freedom Freedom, generally, is having the ability to act or change without c ...

liberty
, not price; all users are legally free to do what they want with their copies of a free software (including profiting from them) regardless of how much is paid to obtain the program.Selling Free Software
(gnu.org)
Computer programs are deemed "free" if they give end-users (not just the developer) ultimate control over the software and, subsequently, over their devices. The right to study and modify a computer program entails that
source code In , source code is any collection of code, with or without , written using a ''human-readable'' , usually as . The source code of a program is specially designed to facilitate the work of computer s, who specify the actions to be performed ...

source code
—the preferred format for making changes—be made available to users of that program. While this is often called "access to source code" or "public availability", the
Free Software Foundation The Free Software Foundation (FSF) is a 501(c)(3) non-profit organization founded by Richard Stallman on October 4, 1985, to support the free software movement, which promotes the universal freedom to study, distribute, create, and modify compu ...
(FSF) recommends against thinking in those terms, because it might give the impression that users have an obligation (as opposed to a right) to give non-users a copy of the program. Although the term "free software" had already been used loosely in the past,
Richard Stallman Richard Matthew Stallman (; born March 16, 1953), also known by his initials, rms, is an American free software movement The free software movement is a social movement Social organisms, including humans, live collectively in interacting popul ...

Richard Stallman
is credited with tying it to the sense under discussion and starting the
free-software movement The free software movement is a social movement with the goal of obtaining and guaranteeing certain freedoms for software users, namely the freedoms to run the software, to study the software, to modify the software, and to share copies of the sof ...
in 1983, when he launched the
GNU Project The GNU Project () is a free software Free software (or libre software) is computer software Software is a collection of Instruction (computer science), instructions and data (computing), data that tell a computer how to work. This i ...
: a collaborative effort to create a freedom-respecting
operating system An operating system (OS) is system software System software is software designed to provide a platform for other software. Examples of system software include operating systems like macOS macOS (; previously Mac OS X and later ...

operating system
, and to revive the spirit of cooperation once prevalent among
hackers A computer A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations automatically. Modern computers can perform generic sets of operations known as Computer program, programs. These progr ...
during the early days of computing.


Context

Free software thus differs from: *
proprietary software Proprietary software, also known as non-free software or closed-source software, is computer software for which the software's publisher or another person reserves some rights from licenses to use, modify, share modifications, or share the softwar ...
, such as
Microsoft Office Microsoft Office, or simply Office, is a family of , , and services developed by . It was first announced by on August 1, 1988, at in . Initially a marketing term for an (bundled set of productivity ), the first version of Office containe ...
,
Google Docs Google Docs is a word processor WordPerfect, first released for minicomputers in 1979 and later ported to microcomputers A word processor (WP) is a device or computer program that provides for input, editing, formatting, and output of text, o ...
, Sheets, and Slides or
iWork iWork is an office suite Productivity software (also called personal productivity software or office productivity software) is application software used for producing information (such as documents, presentations, worksheets, databases, charts, I ...
from
Apple An apple is an edible fruit produced by an apple tree (''Malus domestica''). Apple fruit tree, trees are agriculture, cultivated worldwide and are the most widely grown species in the genus ''Malus''. The tree originated in Central Asia, wher ...
. Users cannot study, change, and share their
source code In , source code is any collection of code, with or without , written using a ''human-readable'' , usually as . The source code of a program is specially designed to facilitate the work of computer s, who specify the actions to be performed ...

source code
. *
freeware Freeware is software Software is a collection of instructions that tell a computer A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations automatically. Modern computers can perform g ...

freeware
, which is a category of proprietary software that does not require payment for basic use. For software under the purview of
copyright Copyright is a type of intellectual property Intellectual property (IP) is a category of property that includes intangible creations of the human intellect. There are many types of intellectual property, and some countries recognize more ...

copyright
to be free, it must carry a
software license A software license is a legal instrument (usually by way of contract law A contract is a legally binding agreement that defines and governs the rights and duties between or among its parties Image:'Hip, Hip, Hurrah! Artist Festival at Sk ...
whereby the author grants users the aforementioned rights. Software that is not covered by copyright law, such as software in the
public domain The public domain consists of all the to which no intellectual property rights apply. Those rights may have expired, been forfeited, expressly waived, or may be inapplicable. As examples, the works of , , and are in the public domain eit ...

public domain
, is free as long as the source code is in the public domain too, or otherwise available without restrictions. Proprietary software uses restrictive software licences or EULAs and usually does not provide users with the source code. Users are thus legally or technically prevented from
changing Change or Changing may refer to: Alteration * Impermanence, a difference in a state of affairs at different points in time * Menopause, also referred to as "the change", the permanent cessation of the menstrual period * Metamorphosis, or change, ...
the software, and this results in reliance on the publisher to provide updates, help, and support. (''See also
vendor lock-in In economics Economics () is the social science that studies how people interact with value; in particular, the Production (economics), production, distribution (economics), distribution, and Consumption (economics), consumption of goods an ...
and
abandonware Abandonware is a product, typically software Software is a collection of Instruction (computer science), instructions and data (computing), data that tell a computer how to work. This is in contrast to Computer hardware, physical hardware, ...
''). Users often may not
reverse engineer Reverse engineering (also known as backwards engineering or back engineering) is a process or method through the application of which one attempts to understand through deductive reasoning Deductive reasoning, also deductive logic, is the process ...

reverse engineer
, modify, or redistribute proprietary software. Beyond copyright law, contracts and lack of source code, there can exist additional obstacles keeping users from exercising freedom over a piece of software, such as
software patent A software patent is a patent NPOV disputes from March 2021 A patent is a Title (property), title that gives its owner the legal right to exclude others from making, using, or selling an invention for a limited period of years in exchange fo ...
s and
digital rights management Digital rights management (DRM) tools or technological protection measures (TPM) are a set of access control In the fields of physical security and information security, access control (AC) is the selective restriction of access to a place o ...
(more specifically,
tivoization Tivoization is the creation of a system that incorporates software Software is a collection of instructions that tell a computer A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations ...
). Free software can be a for-profit, commercial activity or not. Some free software is developed by volunteer
computer programmers A computer programmer, sometimes called a software developer, a programmer or more recently a coder (especially in more informal contexts), is a person who creates computer software Software is a collection of Instruction (computer science ...

computer programmers
while other is developed by corporations; or even by both.


Naming and differences with Open Source

Although both definitions refer to almost equivalent corpora of programs, the Free Software Foundation recommends using the term "free software" rather than "
open-source software Open-source software (OSS) is computer software Software is a collection of Instruction (computer science), instructions and data (computing), data that tell a computer how to work. This is in contrast to Computer hardware, physical hardw ...
" (a younger vision coined in 1998), because the goals and messaging are quite dissimilar. According to the Free Software Foundation, "Open source" and its associated campaign mostly focus on the technicalities of the public development model and marketing free software to businesses, while taking the ethical issue of user rights very lightly or even antagonistically. Stallman has also stated that considering the practical advantages of free software is like considering the practical advantages of not being handcuffed, in that it is not necessary for an individual to consider practical reasons in order to realize that being handcuffed is undesirable in itself. The FSF also notes that "Open Source" has exactly one specific meaning in common English, namely that "you can look at the source code." It states that while the term "Free Software" can lead to two different interpretations, at least one of them is consistent with the intended meaning unlike the term "Open Source". The loan adjective "
libre Libre may refer to: Computing * Libre software, free software * Libre Computer Project, developer of open-hardware single-board computers Music * Libre (Alejandra Guzmán album), ''Libre'' (Alejandra Guzmán album) * Libre (Jennifer Peña album), ...
" is often used to avoid the ambiguity of the word "free" in
English language English is a of the , originally spoken by the inhabitants of . It is named after the , one of the ancient that migrated from , a peninsula on the (not to be confused with ), to the area of later named after them: . Living languages mos ...

English language
, and the ambiguity with the older usage of "free software" as public-domain software. (''See
Gratis versus libre upRichard Stallman illustrating his famous sentence "Think free as in free speech, not free beer" with a beer glass. Libre_Software_Meeting.html"_;"title="Brussels,_Libre_Software_Meeting">RMLL,_9_July_2013 The_English_language.html" ;"titl ...
.'')


Definition and the Four Essential Freedoms of Free Software

The first formal definition of free software was published by FSF in February 1986. That definition, written by
Richard Stallman Richard Matthew Stallman (; born March 16, 1953), also known by his initials, rms, is an American free software movement The free software movement is a social movement Social organisms, including humans, live collectively in interacting popul ...

Richard Stallman
, is still maintained today and states that software is free software if people who receive a copy of the software have the following four freedoms. The numbering begins with zero, not only as a spoof on the common usage of
zero-based numbering Zero-based numbering is a way of numbering in which the initial element of a sequence In mathematics, a sequence is an enumerated collection of objects in which repetitions are allowed and order theory, order matters. Like a Set (mathematics), s ...
in programming languages, but also because "Freedom 0" was not initially included in the list, but later added first in the list as it was considered very important. * Freedom 0: The freedom to the program for any purpose. * Freedom 1: The freedom to how the program works, and change it to make it do what you wish. * Freedom 2: The freedom to and make copies so you can help your neighbour. * Freedom 3: The freedom to the program, and release your improvements (and modified versions in general) to the public, so that the whole community benefits. Freedoms 1 and 3 require
source code In , source code is any collection of code, with or without , written using a ''human-readable'' , usually as . The source code of a program is specially designed to facilitate the work of computer s, who specify the actions to be performed ...

source code
to be available because studying and modifying software without its source code can range from highly impractical to nearly impossible. Thus, free software means that computer users have the freedom to cooperate with whom they choose, and to control the software they use. To summarize this into a remark distinguishing ''libre'' (freedom) software from ''
gratis Gratis may refer to: * Gratis, Ohio, a village in Preble County, US * Gratis Township, Preble County, Ohio, US * Gratis Internet, a US referral marketing company * Free, meaning without charge. See Gratis versus libre See also

* Free (disambig ...
'' (zero price) software, the Free Software Foundation says: "Free software is a matter of liberty, not price. To understand the concept, you should think of 'free' as in '
free speech Freedom of speech is a principle that supports the freedom Freedom, generally, is having the ability to act or change without constraint. Something is "free" if it can change easily and is not constrained in its present state. In philosop ...

free speech
', not as in 'free beer. (''See
Gratis versus libre upRichard Stallman illustrating his famous sentence "Think free as in free speech, not free beer" with a beer glass. Libre_Software_Meeting.html"_;"title="Brussels,_Libre_Software_Meeting">RMLL,_9_July_2013 The_English_language.html" ;"titl ...
.'') In the late 1990s, other groups published their own definitions that describe an almost identical set of software. The most notable are
Debian Free Software GuidelinesThe Debian Free Software Guidelines (DFSG) is a set of guidelines that the Debian Debian (), also known as Debian GNU/Linux, is a Linux distribution A Linux distribution (often abbreviated as distro) is an operating system An operating syst ...
published in 1997, and the
Open Source Definition ''The Open Source Definition'' is a document published by the Open Source Initiative, to determine whether a software license can be labeled with the Open-source software, open-source certification mark. The definition was taken from the exact te ...
, published in 1998. The
BSD The Berkeley Software Distribution (BSD) is a discontinued based on , developed and distributed by the (CSRG) at the . The term "BSD" commonly refers to its descendants, including , , , and . BSD was initially called Berkeley Unix because it ...
-based operating systems, such as
FreeBSD FreeBSD is a free and open-source Free and open-source software (FOSS) is software Software is a collection of Instruction (computer science), instructions and data (computing), data that tell a computer how to work. This is in contrast ...

FreeBSD
,
OpenBSD OpenBSD is a security-focused, free and open-source Free and open-source software (FOSS) is software that is both free software and open-source software where anyone is free software license, freely licensed to use, copy, study, and change ...
, and
NetBSD NetBSD is a based on the (BSD). It was the first open-source BSD descendant officially released after was . It continues to be actively developed and is available for many platforms, including servers, desktops, handheld devices, and s. Th ...

NetBSD
, do not have their own formal definitions of free software. Users of these systems generally find the same set of software to be acceptable, but sometimes see
copyleft Copyleft is the practice of granting the right to freely distribute and modify with the requirement that the same rights be preserved in derivative works created from that property. Copyleft in the form of s can be used to maintain conditions ...

copyleft
as restrictive. They generally advocate permissive free-software licenses, which allow others to use the software as they wish, without being legally to provide the source code. Their view is that this permissive approach is more free. The Kerberos,
X11 The X Window System (X11, or simply X) is a windowing system for bitmap displays, common on Unix-like operating systems. X provides the basic framework for a GUI environment: drawing and moving windows on the display device and interacting with ...
, and
Apache The Apache () are a group of culturally related Native American Native Americans may refer to: Ethnic groups * Indigenous peoples of the Americas, the pre-Columbian peoples of North and South America and their descendants * Native Americans i ...
software licenses are substantially similar in intent and implementation.


Examples

There are thousands of free applications and many operating systems available on the Internet. Users can easily download and install those applications via a
package manager A package manager or package-management system is a collection of software tools that automates the process of installing, upgrading, configuring, and removing computer programs for a computer in a consistent manner. A package manager deals with ...
that comes included with most
Linux distributions A Linux distribution (often abbreviated as distro) is an operating system An operating system (OS) is system software that manages computer hardware, computer software, software resources, and provides common daemon (computing), services for c ...
. The
Free Software DirectoryThe Free Software Directory (FSD) is a project of the Free Software Foundation The Free Software Foundation (FSF) is a 501(c)(3) A 501(c)(3) organization is a corporation, trust, unincorporated association, or other type of organization exempt fr ...
maintains a large database of free-software packages. Some of the best-known examples include the
Linux kernel The Linux kernel is a free and open-source Free and open-source software (FOSS) is software that is both free software and open-source software where anyone is free software license, freely licensed to use, copy, study, and change the softwar ...
, the
BSD The Berkeley Software Distribution (BSD) is a discontinued based on , developed and distributed by the (CSRG) at the . The term "BSD" commonly refers to its descendants, including , , , and . BSD was initially called Berkeley Unix because it ...
and Linux operating systems, the
GNU Compiler Collection The GNU Compiler Collection (GCC) is an optimizing compiler In computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithm of an ...
and
C library The C standard library or libc is the standard library A standard library in computer programming Computer programming is the process of designing and building an executable computer program to accomplish a specific computing result or to per ...
; the
MySQL MySQL () is an open-source Open source is source code that is made freely available for possible modification and redistribution. Products include permission to use the source code, design documents, or content of the product. The open-source m ...
relational database; the
Apache The Apache () are a group of culturally related Native American Native Americans may refer to: Ethnic groups * Indigenous peoples of the Americas, the pre-Columbian peoples of North and South America and their descendants * Native Americans ...
web server; and the
Sendmail Sendmail is a general purpose internetwork Internetworking is the practice of interconnecting multiple computer networks, such that any pair of Host (network), hosts in the connected networks can exchange messages irrespective of their hardware-le ...

Sendmail
mail transport agent. Other influential examples include the
Emacs Emacs or EMACS (Editor MACroS) is a family of text editor A text editor is a type of computer program that edits plain text. Such programs are sometimes known as "notepad" software, following the naming of Microsoft Notepad. Text editors a ...

Emacs
text editor; the
GIMP GIMP ( ; GNU Image Manipulation Program) is a free and open-source raster graphics editor used for image manipulation (retouching) and image editing, free-form drawing, transcoding between different image file formats, and more specialized tas ...

GIMP
raster drawing and image editor; the
X Window System The X Window System (X11, or simply X) is a windowing system for bitmap displays, common on Unix-like A Unix-like (sometimes referred to as UN*X or *nix) operating system An operating system (OS) is system software that manages computer ...
graphical-display system; the
LibreOffice LibreOffice () is a free and open-source productivity software, office productivity software suite, a project of The Document Foundation (TDF). It was fork (software development), forked in 2010 from OpenOffice.org, an open-sourced version of ...

LibreOffice
office suite; and the
TeX TeX (, see below), stylized within the system as TeX, is a typesetting system which was designed and mostly written by Donald Knuth and released in 1978. TeX is a popular means of typesetting complex mathematical formulae; it has been noted ...
and
LaTeX Latex is a stable dispersion (emulsion An emulsion is a mixture of two or more liquids that are normally Miscibility, immiscible (unmixable or unblendable) owing to liquid-liquid phase separation. Emulsions are part of a more general class o ...

LaTeX
typesetting systems.


History

From the 1950s up until the early 1970s, it was normal for computer users to have the ''software freedoms'' associated with free software, which was typically
public-domain software Public-domain software is software Software is a collection of Instruction (computer science), instructions and data (computing), data that tell a computer how to work. This is in contrast to Computer hardware, physical hardware, from which the ...
.
Software Software is a collection of instructions Instruction or instructions may refer to: Computing * Instruction, one operation of a processor within a computer architecture instruction set * Computer program, a collection of instructions Music * I ...

Software
was commonly shared by individuals who used computers and by hardware manufacturers who welcomed the fact that people were making software that made their hardware useful. Organizations of users and suppliers, for example,
SHARE Share may refer to: * Share, to make joint use of a resource (such as food, money, or space); see Sharing * Share (finance), a stock or other financial security (such as a mutual fund) * Share, Kwara, a town and LGA in Kwara State, Nigeria Share ma ...
, were formed to facilitate exchange of software. As software was often written in an interpreted language such as
BASIC BASIC (Beginners' All-purpose Symbolic Instruction Code) is a family of general-purpose, high-level programming language In computer science Computer science deals with the theoretical foundations of information, algorithms and the ar ...

BASIC
, the
source code In , source code is any collection of code, with or without , written using a ''human-readable'' , usually as . The source code of a program is specially designed to facilitate the work of computer s, who specify the actions to be performed ...

source code
was distributed to use these programs. Software was also shared and distributed as printed source code (
Type-in program A type-in program or type-in listing was computer source code In computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic proce ...
) in
computer magazine Computer magazines are about computer A computer is a machine that can be programmed to Execution (computing), carry out sequences of arithmetic or logical operations automatically. Modern computers can perform generic sets of operations kno ...
s (like ''
Creative Computing ''Creative Computing'' was one of the earliest magazines covering the microcomputer revolution. Published from October 1974 until December 1985, the magazine covered the spectrum of hobbyist/home/personal computing in a more accessible format tha ...
'', ''
SoftSide ''SoftSide'' is a defunct computer magazine, begun in October 1978 by Roger Robitaille and published by SoftSide Publications of Milford, New Hampshire. History Dedicated to personal computer programming, ''SoftSide'' was a unique publication with ...
'', ''
Compute! ''Compute!'' (), often stylized as ''COMPUTE!'', was an American home computer Home computers were a class of microcomputers that entered the market in 1977 and became common during the 1980s. They were marketed to consumers as affordable an ...
'', ''
Byte The byte is a unit of digital information that most commonly consists of eight bit The bit is a basic unit of information in computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It ...
'', etc.) and books, like the bestseller ''
BASIC Computer Games ''BASIC Computer Games'' is a compilation of type-in computer games in the BASIC BASIC (Beginners' All-purpose Symbolic Instruction Code) is a family of General-purpose programming language, general-purpose, high-level programming languages wh ...
''. By the early 1970s, the picture changed: software costs were dramatically increasing, a growing software industry was competing with the hardware manufacturer's bundled software products (free in that the cost was included in the hardware cost), leased machines required software support while providing no revenue for software, and some customers able to better meet their own needs did not want the costs of "free" software bundled with hardware product costs. In ''United States vs.
IBM International Business Machines Corporation (IBM) is an American multinational technology company headquartered in Armonk, New York, with operations in over 170 countries. The company began in 1911, founded in Endicott, New York, as the C ...

IBM
'', filed January 17, 1969, the government charged that bundled software was
anti-competitive Anti-competitive practices are business or government practices that unlawfully prevent or reduce competition Competition arises whenever two or more parties strive for a common goal A goal is an idea of the future or desired result tha ...
. While some software might always be free, there would henceforth be a growing amount of software produced primarily for sale. In the 1970s and early 1980s, the
software industry The software industry includes businesses for development Development or developing may refer to: Arts *Development hell, when a project is stuck in development *Filmmaking#Development, Filmmaking, development phase, including finance and bu ...
began using technical measures (such as only distributing binary copies of
computer program In imperative programming, a computer program is a sequence of instructions in a programming language that a computer can execute or interpret. In declarative programming, a ''computer program'' is a Set (mathematics), set of instructions. A comp ...
s) to prevent computer users from being able to study or adapt the software applications as they saw fit. In 1980,
copyright Copyright is a type of intellectual property Intellectual property (IP) is a category of property that includes intangible creations of the human intellect. There are many types of intellectual property, and some countries recognize more ...

copyright
law was extended to computer programs. In 1983,
Richard Stallman Richard Matthew Stallman (; born March 16, 1953), also known by his initials, rms, is an American free software movement The free software movement is a social movement Social organisms, including humans, live collectively in interacting popul ...

Richard Stallman
, one of the original authors of the popular
Emacs Emacs or EMACS (Editor MACroS) is a family of text editor A text editor is a type of computer program that edits plain text. Such programs are sometimes known as "notepad" software, following the naming of Microsoft Notepad. Text editors a ...

Emacs
program and a longtime member of the
hacker A hacker is a person skilled in information technology who uses their technical knowledge to achieve a goal or overcome an obstacle, within a computerized system by non-standard means. Though the term ''hacker'' has become associated in popul ...
community at the MIT Artificial Intelligence Laboratory, announced the
GNU Project The GNU Project () is a free software Free software (or libre software) is computer software Software is a collection of Instruction (computer science), instructions and data (computing), data that tell a computer how to work. This i ...
, the purpose of which was to produce a completely non-proprietary Unix-compatible operating system, saying that he had become frustrated with the shift in climate surrounding the computer world and its users. In his initial declaration of the project and its purpose, he specifically cited as a motivation his opposition to being asked to agree to
non-disclosure agreement #REDIRECT Non-disclosure agreement#REDIRECT Non-disclosure agreement A non-disclosure agreement (NDA), also known as a confidentiality agreement (CA), confidential disclosure agreement (CDA), proprietary information agreement (PIA) or secrecy agre ...
s and restrictive licenses which prohibited the free sharing of potentially profitable in-development software, a prohibition directly contrary to the traditional
hacker ethic The hacker ethic is a philosophy and set of moral values that is common within hacker culture. Practitioners of the hacker ethic believe that sharing information and data with others is an ethical imperative. The hacker ethic is related to the ...
. Software development for the
GNU operating system GNU () is an extensive collection of free software Free software (or libre software) is computer software Software is a collection of Instruction (computer science), instructions and data (computing), data that tell a computer how to ...

GNU operating system
began in January 1984, and the
Free Software Foundation The Free Software Foundation (FSF) is a 501(c)(3) non-profit organization founded by Richard Stallman on October 4, 1985, to support the free software movement, which promotes the universal freedom to study, distribute, create, and modify compu ...
(FSF) was founded in October 1985. He developed a free software definition and the concept of "
copyleft Copyleft is the practice of granting the right to freely distribute and modify with the requirement that the same rights be preserved in derivative works created from that property. Copyleft in the form of s can be used to maintain conditions ...

copyleft
", designed to ensure ''software freedom'' for all. Some non-software industries are beginning to use techniques similar to those used in free software development for their research and development process; scientists, for example, are looking towards more open development processes, and hardware such as microchips are beginning to be developed with specifications released under
copyleft Copyleft is the practice of granting the right to freely distribute and modify with the requirement that the same rights be preserved in derivative works created from that property. Copyleft in the form of s can be used to maintain conditions ...

copyleft
licenses (''see the
OpenCores OpenCores is a community developing digital Digital usually refers to something using digits, particularly binary digits. Technology and computing Hardware *Digital electronics Digital electronics is a field of electronics Electronics c ...
project, for instance'').
Creative Commons Creative Commons (CC) is an American non-profit organization A nonprofit organization (NPO), also known as a non-business entity, not-for-profit organization, or nonprofit institution, is a legal entity organized and operated for a collect ...

Creative Commons
and the
free-culture movement The free-culture movement is a social movement that promotes the freedom to distribute and modify the creative works of others in the form of free content or open content without compensation to, or the consent of, the work's original creators, b ...
have also been largely influenced by the free software movement.


1980s: Foundation of the GNU Project

In 1983,
Richard Stallman Richard Matthew Stallman (; born March 16, 1953), also known by his initials, rms, is an American free software movement The free software movement is a social movement Social organisms, including humans, live collectively in interacting popul ...

Richard Stallman
, longtime member of the
hacker A hacker is a person skilled in information technology who uses their technical knowledge to achieve a goal or overcome an obstacle, within a computerized system by non-standard means. Though the term ''hacker'' has become associated in popul ...
community at the MIT Artificial Intelligence Laboratory, announced the GNU Project, saying that he had become frustrated with the effects of the change in culture of the computer industry and its users. Software development for the GNU operating system began in January 1984, and the
Free Software Foundation The Free Software Foundation (FSF) is a 501(c)(3) non-profit organization founded by Richard Stallman on October 4, 1985, to support the free software movement, which promotes the universal freedom to study, distribute, create, and modify compu ...
(FSF) was founded in October 1985. An article outlining the project and its goals was published in March 1985 titled the ''
GNU Manifesto __NOTOC__ 235px, Richard M. Stallman (cover picture for Free as in Freedom'')">Free as in Freedom: Richard Stallman's Crusade for Free Software">Free as in Freedom'') The ''GNU Manifesto'' is a call-to-action by Richard Stallman Richard Mat ...
''. The manifesto included significant explanation of the GNU philosophy, ''
Free Software Definition The Free Software Definition written by Richard Stallman Richard Matthew Stallman (; born March 16, 1953), also known by his initials, rms, is an American free software movement The free software movement is a social movement A social move ...
'' and "
copyleft Copyleft is the practice of granting the right to freely distribute and modify with the requirement that the same rights be preserved in derivative works created from that property. Copyleft in the form of s can be used to maintain conditions ...

copyleft
" ideas.


1990s: Release of the Linux kernel

The
Linux kernel The Linux kernel is a free and open-source Free and open-source software (FOSS) is software that is both free software and open-source software where anyone is free software license, freely licensed to use, copy, study, and change the softwar ...
, started by
Linus Torvalds Linus Benedict Torvalds ( , ; born 28 December 1969) is a Finnish-American software engineer who is the creator and, historically, the main developer of the Linux kernel, used by Linux distributions and other operating systems such as Android (o ...
, was released as freely modifiable source code in 1991. The first licence was a proprietary software licence. However, with version 0.12 in February 1992, he relicensed the project under the
GNU General Public License The GNU General Public License (GNU GPL or simply GPL) is a series of widely used free software license A free-software license is a notice that grants the recipient of a piece of software extensive rights to modify and software distribu ...
. Much like Unix, Torvalds' kernel attracted the attention of volunteer programmers.
FreeBSD FreeBSD is a free and open-source Free and open-source software (FOSS) is software Software is a collection of Instruction (computer science), instructions and data (computing), data that tell a computer how to work. This is in contrast ...

FreeBSD
and
NetBSD NetBSD is a based on the (BSD). It was the first open-source BSD descendant officially released after was . It continues to be actively developed and is available for many platforms, including servers, desktops, handheld devices, and s. Th ...

NetBSD
(both derived from
386BSD 386BSD (also known as "Jolix") is a discontinued based on the (BSD). It was released in 1992 and ran on computer systems based on the . 386BSD innovations included , s, self-ordered configuration and design. History 386BSD was written ma ...
) were released as free software when the '' USL v. BSDi'' lawsuit was settled out of court in 1993.
OpenBSD OpenBSD is a security-focused, free and open-source Free and open-source software (FOSS) is software that is both free software and open-source software where anyone is free software license, freely licensed to use, copy, study, and change ...
forked from NetBSD in 1995. Also in 1995, The
Apache HTTP Server The Apache HTTP Server, colloquially called Apache ( ), is a free and open-source cross-platform web server software, released under the terms of Apache License 2.0. Apache is developed and maintained by an open community of developers under the ...
, commonly referred to as Apache, was released under the Apache License 1.0.


Licensing

All free-software licenses must grant users all the freedoms discussed above. However, unless the applications' licenses are compatible, combining programs by mixing source code or directly linking binaries is problematic, because of license technicalities. Programs indirectly connected together may avoid this problem. The majority of free software falls under a small set of licenses. The most popular of these licenses are: * The MIT License * The GNU General Public License v2 (GPLv2) * The Apache License * The GNU General Public License v3 (GPLv3) * The
BSD License BSD licenses are a family of permissive free software licenses, imposing minimal restrictions on the use and distribution of covered software. This is in contrast to copyleft Copyleft is the practice of granting the right to freely distrib ...
* The
GNU Lesser General Public License The GNU Lesser General Public License (LGPL) is a free-software license published by the Free Software Foundation (FSF). The license allows developers and companies to use and integrate a software component released under the LGPL into their own ...
(LGPL) * The
Mozilla Public License The Mozilla Public License (MPL) is a free and open-source software license developed and maintained by the Mozilla Foundation. It is a weak copyleft license, characterized as a middle ground between permissive software licenses and the GNU Gen ...
(MPL) * The
Eclipse Public License The Eclipse Public License (EPL) is a free Free may refer to: Concept * Freedom, having the ability to act or change without constraint * Emancipate, to procure political rights, as for a disenfranchised group * Free will, control exercised b ...
The Free Software Foundation and the Open Source Initiative both publish lists of licenses that they find to comply with their own definitions of free software and open-source software respectively: *
List of FSF approved software licenses A ''list'' is any enumeration An enumeration is a complete, ordered listing of all the items in a collection. The term is commonly used in mathematics Mathematics (from Ancient Greek, Greek: ) includes the study of such topics as quantity ( ...
* List of OSI approved software licenses The FSF list is not prescriptive: free-software licenses can exist that the FSF has not heard about, or considered important enough to write about. So it's possible for a license to be free and not in the FSF list. The OSI list only lists licenses that have been submitted, considered and approved. All open-source licenses must meet the
Open Source Definition ''The Open Source Definition'' is a document published by the Open Source Initiative, to determine whether a software license can be labeled with the Open-source software, open-source certification mark. The definition was taken from the exact te ...
in order to be officially recognized as open source software. Free software, on the other hand, is a more informal classification that does not rely on official recognition. Nevertheless, software licensed under licenses that do not meet the Free Software Definition cannot rightly be considered free software. Apart from these two organizations, the
Debian Debian (), also known as Debian GNU/Linux, is a GNU/Linux distribution composed of free and open-source software, developed by the community-supported Debian Project, which was established by Ian Murdock on August 16, 1993. The first version of ...

Debian
project is seen by some to provide useful advice on whether particular licenses comply with their
Debian Free Software GuidelinesThe Debian Free Software Guidelines (DFSG) is a set of guidelines that the Debian Debian (), also known as Debian GNU/Linux, is a Linux distribution A Linux distribution (often abbreviated as distro) is an operating system An operating syst ...
. Debian does not publish a list of licenses, so its judgments have to be tracked by checking what software they have allowed into their software archives. That is summarized at the Debian web site. It is rare that a license announced as being in-compliance with the FSF guidelines does not also meet the
Open Source Definition ''The Open Source Definition'' is a document published by the Open Source Initiative, to determine whether a software license can be labeled with the Open-source software, open-source certification mark. The definition was taken from the exact te ...
, although the reverse is not necessarily true (for example, the NASA Open Source Agreement is an OSI-approved license, but non-free according to FSF). There are different categories of free software. *
Public-domain The public domain consists of all the creative work to which no Exclusive exclusive intellectual property rights apply. Those rights may have expired, been forfeited, expressly waived, or may be inapplicable. As examples, the works of William ...

Public-domain
software: the copyright has expired, the work was not copyrighted (released without
copyright notice In Copyright law of the United States, United States copyright law, a copyright notice is a notice of statutorily prescribed form that informs users of the underlying claim to copyright ownership in a published work. Copyright is a form of prote ...
before 1988), or the author has released the software onto the public domain with a
waiver A waiver is the voluntary wikt:relinquishment, relinquishment or Surrender (law), surrender of some known Rights, right or privilege. Regulatory agencies of state departments or the federal government may issue waivers to exempt companies from ...
statement (in countries where this is possible). Since public-domain software lacks copyright protection, it may be freely incorporated into any work, whether proprietary or free. The FSF recommends the
CC0 A Creative Commons (CC) license is one of several public copyright license A public license or public copyright licenses is a license by which a copyright holder as licensor can grant additional copyright permissions to any and all person ...
public domain dedication for this purpose. *
Permissive licenses A permissive software license, sometimes also called BSD-like or BSD-style license, is a free-software license with only minimal restrictions on how the software can be used, modified, and redistributed, usually including a warranty disclaimer. ...
, also called BSD-style because they are applied to much of the software distributed with the
BSD The Berkeley Software Distribution (BSD) is a discontinued based on , developed and distributed by the (CSRG) at the . The term "BSD" commonly refers to its descendants, including , , , and . BSD was initially called Berkeley Unix because it ...
operating systems: many of these licenses are also known as
copyfree A permissive software license, sometimes also called BSD-like or BSD-style license, is a free-software license A license (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. E ...

copyfree
as they have no restrictions on distribution. The author retains copyright solely to disclaim warranty and require proper attribution of modified works, and permits redistribution and modification, even closed-source ones. In this sense, a permissive license provides an incentive to create non-free software, by reducing the cost of developing restricted software. Since this is incompatible with the spirit of software freedom, many people consider permissive licenses to be less free than copyleft licenses. *
Copyleft Copyleft is the practice of granting the right to freely distribute and modify intellectual property Intellectual property (IP) is a category of property Property is a system of rights that gives people legal control of valuable things ...

Copyleft
licenses, with the
GNU General Public License The GNU General Public License (GNU GPL or simply GPL) is a series of widely used free software license A free-software license is a notice that grants the recipient of a piece of software extensive rights to modify and software distribu ...
being the most prominent: the author retains copyright and permits redistribution under the restriction that all such redistribution is licensed under the same license. Additions and modifications by others must also be licensed under the same "copyleft" license whenever they are distributed with part of the original licensed product. This is also known as a ''viral'', '' protective'', or ''reciprocal'' license. Due to the restriction on distribution not everyone considers this type of license to be free.


Security and reliability

There is debate over the Computer security, security of free software in comparison to proprietary software, with a major issue being security through obscurity. A popular quantitative test in computer security is to use relative counting of known unpatched security flaws. Generally, users of this method advise avoiding products that lack fixes for known security flaws, at least until a fix is available. Free software advocates strongly believe that this methodology is biased by counting more vulnerabilities for the free software systems, since their source code is accessible and their community is more forthcoming about what problems exist, (This is called "Security Through Disclosure") and proprietary software systems can have undisclosed societal drawbacks, such as disenfranchising less fortunate would-be users of free programs. As users can analyse and trace the source code, many more people with no commercial constraints can inspect the code and find bugs and loopholes than a corporation would find practicable. According to Richard Stallman, user access to the source code makes deploying free software with undesirable hidden spyware functionality far more difficult than for proprietary software. Some quantitative studies have been done on the subject.


Binary blobs and other proprietary software

In 2006,
OpenBSD OpenBSD is a security-focused, free and open-source Free and open-source software (FOSS) is software that is both free software and open-source software where anyone is free software license, freely licensed to use, copy, study, and change ...
started the first campaign against the use of binary blobs in Kernel (operating system), kernels. Blobs are usually freely distributable device drivers for hardware from vendors that do not reveal driver source code to users or developers. This restricts the users' freedom effectively to modify the software and distribute modified versions. Also, since the blobs are undocumented and may have Software bug, bugs, they pose a security risk to any
operating system An operating system (OS) is system software System software is software designed to provide a platform for other software. Examples of system software include operating systems like macOS macOS (; previously Mac OS X and later ...

operating system
whose kernel includes them. The proclaimed aim of the campaign against blobs is to collect hardware documentation that allows developers to write free software drivers for that hardware, ultimately enabling all free operating systems to become or remain blob-free. The issue of binary blobs in the
Linux kernel The Linux kernel is a free and open-source Free and open-source software (FOSS) is software that is both free software and open-source software where anyone is free software license, freely licensed to use, copy, study, and change the softwar ...
and other device drivers motivated some developers in Ireland to launch gNewSense, a Linux based distribution with all the binary blobs removed. The project received support from the
Free Software Foundation The Free Software Foundation (FSF) is a 501(c)(3) non-profit organization founded by Richard Stallman on October 4, 1985, to support the free software movement, which promotes the universal freedom to study, distribute, create, and modify compu ...
and stimulated the creation, headed by the Free Software Foundation Latin America, of the Linux-libre kernel. As of October 2012, Trisquel is the most popular FSF endorsed Linux distribution ranked by Distrowatch (over 12 months). While
Debian Debian (), also known as Debian GNU/Linux, is a GNU/Linux distribution composed of free and open-source software, developed by the community-supported Debian Project, which was established by Ian Murdock on August 16, 1993. The first version of ...

Debian
is not endorsed by the FSF and does not use Linux-libre, it is also a popular distribution available without kernel blobs by default since 2011.


Business model

Commercial software, Selling software under any free-software licence is permissible, as is commercial use. This is true for licenses with or without
copyleft Copyleft is the practice of granting the right to freely distribute and modify with the requirement that the same rights be preserved in derivative works created from that property. Copyleft in the form of s can be used to maintain conditions ...

copyleft
. Since free software may be freely redistributed, it is generally available at little or no fee. Free software business models are usually based on adding value such as customization, accompanying hardware, support, training, integration, or certification. Exceptions exist however, where the user is charged to obtain a copy of the free application itself. Fees are usually charged for distribution on compact discs and bootable USB drives, or for services of installing or maintaining the operation of free software. Development of large, commercially used free software is often funded by a combination of user donations, crowdfunding, corporate contributions, and tax money. The SELinux project at the United States National Security Agency is an example of a federally funded free-software project. Proprietary software, on the other hand, tends to use a different business model, where a customer of the proprietary application pays a fee for a license to legally access and use it. This license may grant the customer the ability to configure some or no parts of the software themselves. Often some level of support is included in the purchase of proprietary software, but additional support services (especially for enterprise applications) are usually available for an additional fee. Some proprietary software vendors will also customize software for a fee. The Free Software Foundation encourages selling free software. As the Foundation has written, "distributing free software is an opportunity to raise funds for development. Don't waste it!". For example, the FSF's own recommended license (the GNU GPL) states that "[you] may charge any price or no price for each copy that you convey, and you may offer support or warranty protection for a fee." Microsoft CEO Steve Ballmer stated in 2001 that "open source is not available to commercial companies. The way the license is written, if you use any open-source software, you have to make the rest of your software open source." This misunderstanding is based on a requirement of
copyleft Copyleft is the practice of granting the right to freely distribute and modify with the requirement that the same rights be preserved in derivative works created from that property. Copyleft in the form of s can be used to maintain conditions ...

copyleft
licenses (like the GPL) that if one distributes modified versions of software, they must release the source and use the same license. This requirement does not extend to other software from the same developer. The claim of incompatibility between commercial companies and free software is also a misunderstanding. There are several large companies, e.g. Red Hat and
IBM International Business Machines Corporation (IBM) is an American multinational technology company headquartered in Armonk, New York, with operations in over 170 countries. The company began in 1911, founded in Endicott, New York, as the C ...

IBM
, which do substantial commercial business in the development of free software.


Economic aspects and adoption

Free software played a significant part in the development of the Internet, the World Wide Web and the infrastructure of dot-com companies. Free software allows users to cooperate in enhancing and refining the programs they use; free software is a pure public good rather than a private good. Companies that contribute to free software increase commercial innovation. The economic viability of free software has been recognized by large corporations such as
IBM International Business Machines Corporation (IBM) is an American multinational technology company headquartered in Armonk, New York, with operations in over 170 countries. The company began in 1911, founded in Endicott, New York, as the C ...

IBM
, Red Hat, and Sun Microsystems. Many companies whose core business is not in the IT sector choose free software for their Internet information and sales sites, due to the lower initial capital investment and ability to freely customize the application packages. Most companies in the software business include free software in their commercial products if the licenses allow that. Free software is generally available at no cost and can result in permanently lower TCO costs compared to
proprietary software Proprietary software, also known as non-free software or closed-source software, is computer software for which the software's publisher or another person reserves some rights from licenses to use, modify, share modifications, or share the softwar ...
. With free software, businesses can fit software to their specific needs by changing the software themselves or by hiring programmers to modify it for them. Free software often has no warranty, and more importantly, generally does not assign legal liability to anyone. However, warranties are permitted between any two parties upon the condition of the software and its usage. Such an agreement is made separately from the free software license. A report by Standish Group estimates that adoption of free software has caused a drop in revenue to the
proprietary software Proprietary software, also known as non-free software or closed-source software, is computer software for which the software's publisher or another person reserves some rights from licenses to use, modify, share modifications, or share the softwar ...
industry by about $60 billion per year. Eric S. Raymond argued that the term ''free software'' is too ambiguous and intimidating for the business community. Raymond promoted the term ''
open-source software Open-source software (OSS) is computer software Software is a collection of Instruction (computer science), instructions and data (computing), data that tell a computer how to work. This is in contrast to Computer hardware, physical hardw ...
'' as a friendlier alternative for the business and corporate world.


See also

* Definition of Free Cultural Works * Digital rights * Free content * Libre knowledge * List of formerly proprietary software * List of free software project directories * List of free software for Web 2.0 Services * Open format * Open standard * Open-source hardware * Outline of free software * :Free software lists and comparisons * Appropriate Technology * Sustainable Development


Notes


References


Further reading


Puckette, Miller. "Who Owns our Software?: A first-person case study." eContact (September 2009). Montréal: CEC

Hancock, Terry. "The Jargon of Freedom: 60 Words and Phrases with Context". Free Software Magazine. 2010-20-24
*


External links

{{Authority control Free software, Software licenses Applied ethics