Editing Software license (section)

== Free and open-source software licenses ==
{{Main|Free software license|Open-source license}}

Before the open-source movement in the 1980s, almost all software was proprietary and did not disclose its [[source code]].{{sfn|Bernelin|2020|p=96}} Open-source licensing is intended to maximize openness and minimize barriers to software use, dissemination, and follow-on innovation.{{sfn|Morin ''et al.''|2012|loc=Free and Open Source Software (FOSS) Licensing}} 

Open-source licenses share a number of key characteristics:{{sfn|Sen|Subramaniam|Nelson|2008|p=209}}
*Free redistribution: Anyone can redistribute the software, for free or for cost, without the permission of or payment to the copyright holder.{{sfn|Sen|Subramaniam|Nelson|2008|p=209}}
* Unrestricted, public access to the [[source code]]{{sfn|Sen|Subramaniam|Nelson|2008|p=209}}—what the term ''open source'' refers to{{sfn|Morin ''et al.''|2012|loc=Open Source versus Closed Source}}
* Users may modify the software and release [[derivative work]]s, either under the same terms as the free software or, in some cases, under a different license.{{sfn|Sen|Subramaniam|Nelson|2008|p=209}}
*Nondiscrimination between different uses,{{sfn|Sen|Subramaniam|Nelson|2008|p=209}} including commercial use.{{sfn|Davila|2015|p=6}}{{sfn|Morin ''et al.''|2012|loc=Free and Open Source Software (FOSS) Licensing}}
The [[Open Source Initiative]] vets and approves new open-source licenses that comply with its [[Open Source Definition]].{{sfn|Sen|Subramaniam|Nelson|2008|p=209}} 

===Types of open-source licenses===
[[File:Open-source-license-chart.svg|thumb|alt=A pie chart displays the most commonly used open source license as Apache at 30%, MIT at 26%, GPL at 18%, BSD at 8%, LGPL at 3%, MPL at 2%, and remaining 13% as licenses with below 1% market share each.|The most popular open source licenses as of 2022 are the [[Apache License]] (permissive), the [[MIT License]] (permissive), and the [[GNU General Public License|GPL]] (copyleft).]]

*If software is in the [[public domain]], the owner's copyright has been extinguished and anyone may use the work with no copyright restrictions.{{sfn|O'Regan|2022|p=403}}
*Non-restrictive licenses allow free reuse of the work without restrictions on the licensing of [[derivative work]]s.{{sfn|Sen|Subramaniam|Nelson|2008|p=212}} Many of them require attribution of the original creators.{{sfn|Morin ''et al.''|2012|loc=Permissive versus Copyleft}} The first open-source license was a non-restrictive license intended to facilitate scientific collaboration: the [[Berkeley Software Distribution]] (BSD), named after the [[University of California, Berkeley]] in 1978.{{sfn|Smith|2022|loc=§&nbsp;3.2.1.1}}
*[[Copyleft]] licenses (also known as "share-alike"),{{sfn|Morin ''et al.''|2012|loc=Permissive versus Copyleft}} require [[source code]] to be distributed with software and require the source code be made available under a similar license.{{sfn|Sen|Subramaniam|Nelson|2008|pp=211-212}}{{sfn|St. Laurent|2004|pp=38-39}} Copyleft represents the farthest that reuse can be restricted while still being considered free software.{{sfn|Davila|2015|p=5}} Strong copyleft licenses, such as the [[GNU General Public License]] (GPL), allow for no reuse in proprietary software, while weak copyleft, such as the related [[GNU Lesser General Public License]] (LGPL), do allow reuse in some circumstances.{{sfn|Sen|Subramaniam|Nelson|2008|p=212}} Copyleft licenses are perceived by developers as a way of ensuring that their contributions do not create unfair advantages for others.{{sfn|Sen|Subramaniam|Nelson|2008|p=212}}{{sfn|Davila|2015|pp=5-6}} Another motivation for choosing  copyleft is to promote open source through its requirements for derivative works:{{sfn|Morin ''et al.''|2012|loc=Permissive versus Copyleft}} [[Richard Stallman|Stallman]] states that "the central idea of copyleft is to use copyright law, but flip it over to serve the opposite of its usual purpose: instead of a means of privatizing software, [copyright] becomes a means of keeping software free."{{sfn|Joy|2022|pp=990-992}} 

Outside of software, noncommercial-only [[Creative Commons]] licenses have become popular among some artists who wish to prevent others from profiting excessively from their work.{{sfn|Davila|2015|pp=5-6}} However, software that is made available for [[noncommercial]] use only is not considered open source.{{sfn|Davila|2015|p=6}} [[Sun Microsystems]]' noncommercial-only [[Java Research License]] was rejected by the open-source community, and in 2006 the company released most of Java under the GPL.{{sfn|Davila|2015|p=6}}

===Compatibility===
{{see also|License compatibility}}
[[File:GPL-Compatible.svg|thumb|upright=1.5|Compatibility chart for some open-source software licenses]]
Since 1989,{{sfn|Bernelin|2020|p=96}} a variety of [[open-source license]]s for software have been created.{{sfn|Sen|Subramaniam|Nelson|2008|p=208}} Choosing an open-source software license has grown increasingly difficult due to the [[license proliferation|proliferation of licenses]],{{sfn|Alamoudi ''et al.''|2020|p=537}}{{sfn|Bernelin|2020|p=94}} many of which are only trivially distinct.{{sfn|Morin ''et al.''|2012|loc=Compatibility, Proliferation, Fragmentation, and Directionality}} Many licenses are incompatible with each other, hampering the goals of the free software movement.{{sfn|Bernelin|2020|p=98}} Translation issues, ambiguity in licensing terms, and incompatibility of some licenses with the law in certain jurisdictions compounds the problem.{{sfn|Bernelin|2020|pp=100, 102}} 

Although downloading an open-source module is quick and easy, complying with the licensing terms can be more difficult.{{sfn|Ombredanne|2020|p=105}} The amount of software dependencies means that engineers working on complex projects must often rely on software license management software in order to help them achieve compliance with the licensing terms of open-source components.{{sfn|Ombredanne|2020|p=106}} Many open-source software files do not unambiguously state the license, increasing the difficulties of compliance.{{sfn|Ombredanne|2020|p=105}} When combining code bases, the original licenses can be maintained for separate components, and the larger work released under a compatible license.{{sfn|St. Laurent|2004|pp=159-163}} This compatibility is often one-way. Public domain content can be used anywhere as there is no copyright claim, but code acquired under almost any set of terms cannot be waved to the public domain. Permissive licenses can be used within copyleft works, but copyleft material cannot be released under a permissive license. Some weak copyleft licenses can be used under the GPL and are said to be GPL-compatible. GPL software can only be used under the GPL or AGPL.{{sfn|Smith|2022|loc=§&nbsp;3.3}}

===Enforceability===
{{further|Open source license litigation}}
Free and open-source software licenses have been successfully [[Open source license litigation|enforced in civil]] court since the mid-2000s.{{sfn|Smith|2022|loc=§&nbsp;3.4.1}} Courts have found that distributing software indicates acceptance of the license's terms.{{sfn|Smith|2022|p=106}} However, developers typically achieve compliance without lawsuits. [[Social pressure]]s, such as the potential for community backlash, are often sufficient.{{sfn|St. Laurent|2004|pp=158-159}} [[Cease and desist]] letters are a common method to bring companies back into compliance, especially in Germany.{{sfn|Ballhausen|2022|p=127}}

A long-debated subject within the FOSS community is whether open-source licenses are "bare licenses" or [[contract]]s.{{sfn|Walden|2022|loc=§&nbsp;1.1}} A bare license is a set of conditions under which actions otherwise restricted by [[intellectual property]] laws are permitted.{{sfn|Smith|2022|loc=§&nbsp;3.4.1}} Under the bare license interpretation, advocated by the [[Free Software Foundation]] (FSF), a case is brought to court by the copyright holder as [[copyright infringement]].{{sfn|Smith|2022|loc=§&nbsp;3.4.1}} Under the contract interpretation, a case can be brought to court by an involved party as a [[breach of contract]].{{sfn|Smith|2022|loc=§&nbsp;3.4.2}} United States and French courts have tried cases under both interpretations.{{sfn|Smith|2022|loc=§&nbsp;3.4}}

===Value===
More than 90 percent of companies use open-source software as a component of their proprietary software.{{sfn|Butler ''et al.''|2022|p=1}} The decision to use open-source software, or even engage with open-source projects to improve existing open-source software, is typically a pragmatic business decision.{{sfn|Butler ''et al.''|2022|p=11152}}{{sfn|Davila|2015|p=7}} When proprietary software is in direct competition with an open-source alternative, research has found conflicting results on the effect of the competition on the proprietary product's price and quality.{{sfn|Zhou |Choudhary|2022|p=731}}

For decades, some companies have made servicing of an open-source software product for enterprise users as their business model. These companies control an open-source software product, and instead of charging for licensing or use, charge for improvements, integration, and other servicing.{{sfn|August ''et al.''|2021|pp=1-2}} [[Software as a service]] (SaaS) products based on open-source components are increasingly common.{{sfn|August ''et al.''|2021|p=1}} 

Open-source software is preferred for scientific applications, because it increases transparency and aids in the validation and acceptance of scientific results.{{sfn|Morin ''et al.''|2012|loc=Compatibility, Proliferation, Fragmentation, and Directionality}}