Copyleft - Wikipedia Jump to content Main menu Main menu move to sidebar hide Navigation Main page Contents Current events Random article About Wikipedia Contact us Contribute Help Learn to edit Community portal Recent changes Upload file Special pages Search Search Appearance Donate Create account Log in Personal tools Donate Create account Log in Contents move to sidebar hide (Top) 1 History 2 Principles Toggle Principles subsection 2.1 Freedom 2.2 Reciprocity 2.3 Economic incentive 3 Application 4 Types and relation to other licenses Toggle Types and relation to other licenses subsection 4.1 Strong and weak copyleft 4.2 Full and partial copyleft 4.3 Share-alike 4.4 Permissive licenses 5 Debate and controversy Toggle Debate and controversy subsection 5.1 "Viral" licensing 6 Symbol 7 See also 8 References 9 External links Toggle the table of contents Copyleft 63 languages Afrikaans Alemannisch العربية Asturianu Azərbaycanca Беларуская (тарашкевіца) Български বাংলা Català Čeština Dansk Deutsch Ελληνικά Esperanto Español Eesti Euskara فارسی Suomi Français Galego עברית हिन्दी Hrvatski Magyar Հայերեն Interlingua Bahasa Indonesia Íslenska Italiano 日本語 Qaraqalpaqsha 한국어 Kurdî Latina Lombard Lietuvių Latviešu Олык марий Македонски മലയാളം Bahasa Melayu Nederlands Norsk nynorsk Norsk bokmål Polski Português Română Русский Srpskohrvatski / српскохрватски Simple English Slovenčina Slovenščina Српски / srpski Svenska தமிழ் తెలుగు ไทย Türkçe Українська Tiếng Việt 吴语 中文 Edit links Article Talk English Read Edit View history Tools Tools move to sidebar hide Actions Read Edit View history General What links here Related changes Upload file Permanent link Page information Cite this page Get shortened URL Switch to legacy parser Print/export Download as PDF Printable version In other projects Wikimedia Commons Wikidata item Appearance move to sidebar hide From Wikipedia, the free encyclopedia Preservation of legal rights in the reuse of a work Copyleft symbol Intellectual property Authors' rights Copyleft Copyright Database right Farmers' rights Geographical indication Indigenous intellectual property Industrial design right Integrated circuit layout design protection Intellectual property infringement Literary property Moral rights Patent Peasants' rights Plant breeders' rights Plant genetic resources Proprietary software Related rights Sound recording copyright Supplementary protection certificate Trade dress Trade secret Trademark Utility model Patent infringement Related topics Abandonware Artificial intelligence and copyright Brand protection Copyright abolition Copyright troll Criticism of copyright Bioprospecting Biopiracy Idea–expression distinction Limitations and exceptions to copyright Fair dealing Fair use Paraphrasing Right to quote Orphan work Patent troll Pirate Party Public domain Outline of intellectual property Outline of patents Higher categories: Property and Property law v t e Copyleft Articles on copyleft licensing Topics Copyleft Open-source license Free-software license Free and open-source software Royalty-free Higher categories: Software, freedom Category:Free and open-source software licenses v t e Copyleft is the legal technique of granting certain freedoms over copies of copyrighted works with the requirement that the same rights be preserved in derivative works. In this sense, freedoms refers to the use of the work for any purpose, and the ability to modify, copy, share, and redistribute the work, with or without a fee. Licenses which implement copyleft can be used to maintain copyright conditions for works ranging from computer software, to documents, art, and scientific discoveries. Similar approaches have been applied to certain patents.[1] Copyleft software licenses are considered protective or reciprocal (in contrast with permissive free software licenses):[2] they require that information necessary for reproducing and modifying the work be made available to recipients of the software program.[citation needed] This information is most commonly in the form of source code files, which usually contain a copy of the license terms and acknowledge the authors of the code. Copyleft licenses are designed to ensure that the same rights granted to users by the work's authors are preserved when that work (or modified versions of it) are redistributed. Notable copyleft licenses include the GNU General Public License (GPL), originally written by Richard Stallman, which was the first software copyleft license to see extensive use; the Mozilla Public License; the Free Art License; and the Creative Commons share-alike license condition—with the last two intended for non-software works, such as documents and pictures, both academic or artistic in nature.[3] Wikipedia is copyleft under the Creative Commons Attribution-ShareAlike license.[4] History [edit] Li-Chen Wang's Palo Alto Tiny BASIC for the Intel 8080 appeared in Dr. Dobb's Journal in May 1976. The listing begins with the title, author's name, and date, but also has "@COPYLEFT ALL WRONGS RESERVED".[3][5] The concept of copyleft was described in Richard Stallman's GNU Manifesto in 1985, where he wrote:[6] GNU is not in the public domain. Everyone will be permitted to modify and redistribute GNU, but no distributor will be allowed to restrict its further redistribution. That is to say, proprietary modifications will not be allowed. I want to make sure that all versions of GNU remain free. Stallman's motivation was that a few years earlier he had worked on a Lisp interpreter. Symbolics asked to use the Lisp interpreter, and Stallman agreed to supply them with a public domain version of his work. Symbolics extended and improved the Lisp interpreter, but when Stallman wanted access to the improvements that Symbolics had made to his interpreter, Symbolics refused. Stallman then, in 1984, proceeded to work towards eradicating this emerging behavior and culture of proprietary software, which he named software hoarding. This was not the first time Stallman had dealt with proprietary software, but he deemed this interaction a "turning point". He justified software sharing, protesting that when sharing, the software online can be copied without the loss of the original piece of work. The software can be used multiple times without ever being damaged or worn out.[7][8] As Stallman deemed it impractical in the short term to eliminate current copyright law and the wrongs he perceived it to perpetuate, he decided to work within the framework of existing law; in 1985,[9] he created his own copyright license, the Emacs General Public License,[10] the first copyleft license. This later evolved into the GNU General Public License, which is now one of the most popular free-software licenses. For the first time, a copyright holder had taken steps to ensure that the maximal number of rights be perpetually transferred to a program's users, no matter what subsequent revisions anyone made to the original program. This original GPL did not grant rights to the public at large, only those who had already received the program; but it was the best that could be done under existing law. The new license was not at this time given the copyleft label.[11] Richard Stallman stated that the use of "Copyleft" comes from Don Hopkins, who mailed him a letter in 1984 or 1985, on which was written: "Copyleft – all rights reversed", which is a pun on the common copyright disclaimer "all rights reserved".[11] In France, a series of meetings taking place in 2000 under the title "Copyleft Attitude" gave birth to the Free Art License (FAL),[12] theoretically valid in any jurisdiction bound by the Berne Convention and recommended by Stallman's own Free Software Foundation.[13] Shortly thereafter, a separate, unrelated initiative in the United States yielded the Creative Commons license, available since 2001 in both permissive (BY) and copyleft (BY-SA) variants and more specifically tailored to US law. Principles [edit] Freedom [edit] While copyright law gives software authors control over copying, distribution and modification of their works, the goal of copyleft is to give all users of the work the freedom to carry out all of these activities. The Free Software Definition lists "four essential freedoms" of software use:[7][14] The freedom to run the program as you wish, for any purpose (freedom 0). The freedom to study how the program works, and change it so it does your computing as you wish (freedom 1). Access to the source code is a precondition for this. The freedom to redistribute copies so you can help others (freedom 2). The freedom to distribute copies of your modified versions to others (freedom 3). By doing this you can give the whole community a chance to benefit from your changes. Access to the source code is a precondition for this. Similar terms are present in the Open Source Definition, a separate definition that contains similar freedoms. The vast majority of copyleft licenses satisfy both definitions, that of the Free Software Definition and Open Source Definition.[7] By guaranteeing viewers and users of a work the freedom and permission to reproduce, adapt, or distribute it, copyleft licenses are distinct from other types of copyright licenses that limit such freedoms. Reciprocity [edit] Instead of allowing a work to fall completely into the public domain, where no ownership of copyright is claimed, copyleft allows authors to impose restrictions on the use of their work. One of the main restrictions imposed by copyleft is that derived works must also be released under a compatible copyleft license.[7] This is due to the underlying principle of copyleft: that anyone can benefit freely from the previous work of others, but that any modifications to that work should benefit everyone else as well, and thus must be released under similar terms. For this reason, copyleft licenses are also known as reciprocal licenses: any modifiers of a copyleft-licensed work are expected to reciprocate the author's action of copyleft-licensing the software by also copyleft-licensing any derivatives they might have made. Because of this requirement, copyleft licenses have also been described as "viral" due to their self-perpetuating terms.[15] In addition to restrictions on copying, copyleft licenses address other possible impediments. They ensure that rights cannot be later revoked, and require the work and its derivatives to be provided in a form that allows further modifications to be made. In software, this means requiring that the source code of the derived work be made available together with the software itself.[7] Economic incentive [edit] The economic incentives to work on copyleft works can vary. Copyright law was originally intended to promote progress by encouraging economic benefits to authors. When choosing to copyleft their work, authors may seek complementary benefits like recognition from their peers. In the world of computer programming, copyleft-licensed computer programs are often created by programmers to fill a need they have noticed. Such programs are often published with a copyleft license simply to ensure that subsequent users can also freely use modified versions of that program. This is especially true for authors who wish to prevent proprietarization, or the act of reusing free software and then adding extra restrictions to it, an action prevented by copyleft-licensing the software. Some businesses, such as Elastic[16], feel that preventing commercial enterprises from using and then selling their product under a proprietary license is also an incentive. Furthermore, the open-source culture of programming has been described as a gift economy, where social power is determined by an individual's contributions.[17…