Editing Open-source license (section)

===Permissive===
{{main|Permissive software license}}

[[File:MIT Dome night1 Edit.jpg|alt=M I T campus at night|thumb|Permissive licenses generally originate in academic institutions like the [[Massachusetts Institute of Technology]].]]

[[Permissive software license|Permissive licenses]], also known as academic licenses,{{sfn|Rosen|2005|p=69}} allow recipients to use, modify, and distribute software with no obligation to provide source code. Institutions created these licenses to distribute their creations to the public.{{sfn|Rosen|2005|p=69}} Permissive licenses are usually short, often less than a page of text. They impose few [[wikt:condition#Noun|conditions]]. Most include disclaimers of warranty and obligations to [[Credit (creative arts)|credit]] authors. A few include explicit provisions for patents, trademarks, and other forms of intellectual property.{{sfn|Rosen|2005|pp=101-102}}

The [[University of California, Berkeley]] created the first open-source license when they began distributing their [[Berkeley Software Distribution]] (BSD) operating system. The [[BSD license]] and its later variations permit modification and distribution of the covered software. The [[BSD license]]s brought the concept of academic freedom of ideas to computing. Early academic software authors had shared code based on implied promises. Berkeley made these concepts explicit with clear disclaimers for liability and warranty along with conditions, or [[wikt:clause#Noun|clauses]], for redistribution. The original had four clauses, but subsequent versions have further reduced the restrictions. As a result, it is common to specify if the covered software uses a 2-clause or 3-clause version.{{sfn|Smith|2022|loc=sec.&nbsp;3.2.1.1}}{{sfn|OSI|2023}}

The [[Massachusetts Institute of Technology]] (MIT) created an academic license based on the BSD original. The [[MIT license]] clarified the conditions by making them more explicit.{{sfn|Rosen|2005|pp=73-90}} For example, the MIT license describes the right to [[wikt:sublicense#English|sublicense]].{{sfn|OSI|2023|loc="The MIT License"}} One of the strengths of open-source development is the continual process where developers can build on the derivative works of each other and combine their projects into collective works. Explicitly making covered code sublicensable provides a legal advantage when tracking the chain of authorship.{{sfn|Rosen|2005|pp=73-90}} The BSD and MIT are template licenses that can be adapted to any project. They are widely adapted and used by many FOSS projects.{{sfn|Smith|2022|loc=sec.&nbsp;3.2.1.1}}

The [[Apache License]] is more comprehensive and explicit. [[The Apache Software Foundation]] wrote it for their [[Apache HTTP Server]]. Version 2, published in 2004, offers legal advantages over simple licenses and provides similar grants.{{sfn|Smith|2022|loc=sec.&nbsp;3.2.1.2}} While the BSD and MIT licenses offer an implicit patent grant,{{sfn|Bain|Smith|2022|loc=sec.&nbsp;10.4.2}} the Apache License includes a section on patents with an explicit grant from contributors.{{sfn|OSI|2023|loc="Apache License, Version 2.0"}} Additionally, it is one of the few permissive licenses with a patent retaliation clause.{{sfn|Bain|Smith|2022|loc=ch.&nbsp;10}} Patent retaliation, or patent suspension, clauses take effect if a [[wikt:licensee#English|licensee]] initiates [[patent infringement]] litigation on covered code. In that situation, the patent grants are revoked. These clauses protect against [[patent trolling]].{{sfn|Bain|Smith|2022|loc=sec.&nbsp;10.4.4}}