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
, 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](_blank)
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
—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
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,
is credited with tying it to the sense under discussion and starting the free-software movement
in 1983, when he launched the GNU Project
: a collaborative effort to create a freedom-respecting operating system
, and to revive the spirit of cooperation once prevalent among hackers
during the early days of computing.
Free software thus differs from:
* proprietary software
, such as Microsoft Office
, Google Docs
, and Slides
. Users cannot study, change, and share their source code
, which is a category of proprietary software that does not require payment for basic use.
For software under the purview of copyright
to be free, it must carry a software license
whereby the author grants users the aforementioned rights. Software that is not covered by copyright law, such as software in the 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
the software, and this results in reliance on the publisher to provide updates, help, and support. (See also vendor lock-in
). Users often may not 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
s and digital rights management
(more specifically, tivoization
Free software can be a for-profit, commercial activity or not. Some free software is developed by volunteer 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
" (a younger vision coined in 1998), because the goals and messaging are quite dissimilar. "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
" is often used to avoid the ambiguity of the word "free" in English language
, and the ambiguity with the older usage of "free software" as public-domain software.
See ''Gratis'' versus ''libre''
Definition and the Four Essential Freedoms of Free Software
The first formal definition of free software was published by Free Software Foundation (FSF)
in February 1986.
That definition, written by 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
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 ''run'' the program for any purpose.
* Freedom 1: The freedom to ''study'' how the program works, and change it to make it do what you wish.
* Freedom 2: The freedom to ''redistribute'' and make copies so you can help your neighbour.
* Freedom 3: The freedom to ''improve'' 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
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
'' (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
', not as in 'free beer.
See ''Gratis'' versus ''libre''
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 Guidelines
published in 1997,
and the Open Source Definition
, published in 1998.
-based operating systems, such as FreeBSD
, and 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
as restrictive. They generally advocate permissive free-software licenses
, which allow others to use the software as they wish, without being legally ''forced'' to provide the source code. Their view is that this permissive approach is more free. The Kerberos
, and Apache
software licenses are substantially similar in intent and implementation.
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
that comes included with most Linux distributions
The Free Software Directory
maintains a large database of free-software packages. Some of the best-known examples include the Linux kernel
, the BSD
and Linux operating systems, the GNU Compiler Collection
and C library
; the MySQL
relational database; the Apache
web server; and the Sendmail
mail transport agent. Other influential examples include the Emacs
text editor; the GIMP
raster drawing and image editor; the X Window System
graphical-display system; the LibreOffice
office suite; and the TeX
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
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
, were formed to facilitate exchange of software. As software was often written in an interpreted language such as BASIC
, the source code
was distributed to use these programs. Software was also shared and distributed as printed source code (Type-in program
) in computer magazine
s (like Creative Computing
etc) and books, like the bestseller ''BASIC Computer Games
''. 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
'', filed January 17, 1969, the government charged that bundled software was anti-competitive
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
began using technical measures (such as only distributing binary copies
of computer program
s) to prevent computer users
from being able to study or adapt the software applications as they saw fit. In 1980, copyright
law was extended to computer programs.
In 1983, Richard Stallman
, one of the original authors of the popular Emacs
program and a longtime member of the hacker
community at the MIT Artificial Intelligence Laboratory
, announced the GNU project
, 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
s and restrictive licenses which prohibited the free sharing of potentially profitable in-development software, a prohibition directly contrary to the traditional hacker ethic
. Software development for the GNU operating system
began in January 1984, and the Free Software Foundation
(FSF) was founded in October 1985. He developed a free software definition and the concept of "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
licenses (see the OpenCores
project, for instance). Creative Commons
and the free-culture movement
have also been largely influenced by the free software movement.
1980s: Foundation of the GNU project
In 1983, Richard Stallman
, longtime member of the hacker
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
(FSF) was founded in October 1985. An article outlining the project and its goals was published in March 1985 titled the GNU Manifesto
. The manifesto included significant explanation of the GNU philosophy, ''Free Software Definition
'' and "copyleft
1990s: Release of the Linux kernel
The Linux kernel
, started by Linus Torvalds
, 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
. Much like Unix, Torvalds' kernel attracted the attention of volunteer programmers.
(both derived from 386BSD
) were released as free software when the USL v. BSDi
lawsuit was settled out of court in 1993. OpenBSD forked
from NetBSD in 1995. Also in 1995, The Apache HTTP Server
, commonly referred to as Apache, was released under the Apache License 1.0
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
* The Apache License
* The GNU General Public License v3
* The BSD License
* The GNU Lesser General Public License
* The Mozilla Public License
* The Eclipse Public License
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
* 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
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
project is seen by some to provide useful advice on whether particular licenses comply with their Debian Free Software Guidelines
. Debian doesn't publish a list of ''approved'' 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
, 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.
software: the copyright has expired, the work was not copyrighted (released without copyright notice
before 1988), or the author has released the software onto the public domain with a waiver
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
public domain dedication for this purpose.
* Permissive licenses
, also called BSD-style because they are applied to much of the software distributed with the BSD
operating systems: many of these licenses are also known as 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 any 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.
licenses, with the GNU General Public License
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''
'', 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 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
started the first campaign against the use of binary blob
s in kernels
. Blobs are usually freely distributable device driver
s 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 bugs
, they pose a security risk to any 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
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
and stimulated the creation, headed by the Free Software Foundation Latin America
, of the Linux-libre
As of October 2012, Trisquel
is the most popular FSF endorsed Linux distribution ranked by Distrowatch (over 12 months).
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.
under any free-software licence is permissible, as is commercial use. This is true for licenses with or without 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 "ou
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
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
, 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
, 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
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
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
'' as a friendlier alternative for the business and corporate world.
* 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
* :Category:Free software lists and comparisons
* Appropriate Technology
* Sustainable Development
Puckette, Miller. "Who Owns our Software?: A first-person case study." eContact (September 2009). Montréal: CECHancock, Terry. "The Jargon of Freedom: 60 Words and Phrases with Context". Free Software Magazine. 2010-20-24