There are variations, of coursethe lgpl, for example, is a weak. In contrast, copyleft licences like the gnu general public license require copies and derivatives of the source code to be made available on terms not more restrictive than those of the original licence. Copyleft is a legal concept drafted by programmer richard stallman, which allows the further distribution and modification of software released under the terms of a copyleft licence, but it does not allow proprietary developers to come and close the released software by not offering access to the source code. A site license allows a single key to be used to install an application on multiple machines at a specific location, but the maximum number of usersmachines is still limited by. Creative commons is a nonprofit corporation dedicated to making it easier for people to share and build upon the work of others, consistent with the rules of. Jul 29, 2016 copyleft licensing is favourable for software coders. The first type of software license which we will cover here is known as the gnu gpl, or simply the gpl license.
A very fast tutorial on open source licenses contact and. If you want you can read the full text of the attributionsharealike 3. Much widelyused code is released under copyleft licenses, especially the gpl, but much is also released under noncopyleft licenses. Copylefted definition of copylefted by the free dictionary. It is a legal instrument that requires those who pass on a program to include. End user license agreement unrestricted software important please read carefully. These are your weak copyleft licenses, copyleft meaning some part of the derived work also has to be released under the same license.
A creative commons cc license is one of several public licenses that enable the free distribution of an otherwise ed work. Non copyleft licenses will dominate for large oss projects. A site license allows an unlimited number of employees at a single location to use a software app simultaneously. Similar to the agpl, the open software licenses requires you to disclose your source code when you communicate software which includes cloudhosted distribution. Copyleft licensing is favourable for software coders. In other words, a copyleft license prevents people from taking freely available material, altering it and then selling it as proprietary material. Copylefting software makes clear the intent of never. Permissive software license simple english wikipedia.
Free software licenses can be divided into two broad categories. Below is a quick rundown of common software licenses and how theyve evolved over the decades. A copyleft license uses to forbid forbidding changing, giving, or selling something. This end user license agreement eula is a legal agreement between you either an individual or a company licensee and zebra technologies corporation zebra for software, owned by zebra and its affiliated companies and its thirdparty suppliers and. From beerware licensing, where you need to buy a beer for the open source programmer if you see them in a bar, to the finetuned and legallycurated berkeley software distribution bsd license, we have it all. Software manufacturers were not only concerned about deliberate piracy by computer hackers. Ive led the drafting of one major copyleft license, actively participated in the drafting of at least four others, and given passing comments to more. In the gnu project, the specific distribution terms that we use for most software are contained in the gnu general public license. There are variations, of coursethe lgpl, for example, is a weak copyleft. Other parts may be distributed under other licences, even though they form part of a work which is as a whole a modified version of your code. A permissive free software licence is a free software licence for a ed work that offers freedoms such as publishing a work to the public domain. Copyleft is a general concept, and you cant use a general concept directly. Gnu general public license v3 gpl3 369497 code license managed by kevin.
Gnu general public license version 3 open source initiative. There are many variants of simple noncopyleft free software licenses, such as the expat license, freebsd license, x10 license, the x11 license, and the two bsd berkeley software distribution licenses. It is not the opposite of, but its purpose is the opposite of the purpose of the frequently seen type of license which uses to forbid changing, giving, or selling something. Copyleft licensing article about copyleft licensing by.
The earliest copyleft licenses were specific to various gnu programs. The free software component that is part of the composite is only available under a strong copyleft license no permissive license, no dual license. The gnu general public license gnu gpl or simply gpl is a widely used free software license, originally written by richard stallman for the gnu project. Nov 10, 2010 in other words, a copyleft license prevents people from taking freely available material, altering it and then selling it as proprietary material. On the other hand, mostrestrictive or strongcopyleft licenses will be the dominant license when minimal effort is required to develop the original oss and the derivative. The use of software licenses for non software work is generally discouraged. Most copylefted software is issued under the gnu general public license gpl, which was the first copyleft license and by far the most commonly used license for free software. Working with usedsoft offers you compelling benefits. The internet provides a suitable platform for sharing and developing source code and open collaboration results in faster and more efficient development. Under this philosophy, the gpl grants the recipients of a computer program. One way to make money with copylefted works is to sell consultancy and support for users of a copylefted work.
So i think it is important to understand how copyleft is or isnt. You must provide free copies of the software if you use it. By contrast, the gnu general public license is intended to guarantee your freedom to share and change all versions of a programto make sure it remains free software for all its users. Copyleft is a name for a type of a license for free content or free software. For most of its history for 16 years from june 1991 to june 2007 there was really only one version of the gpl, version 2. Copyleft licensing article about copyleft licensing by the. What are some examples of sharealikecopyleft licenses. The free software component that is part of the composite is only available under a strong copyleft license no permissive license, no duallicense. Weak copyleft, on the other hand, means that when software contains some of your code, some parts of the software must be distributed under your licence, if the software is distributed at all. The economic focus tends to be on monetizing other scarcities, complimentary goods rather than the free content itself. Copyleft, distinguished from, is the practice of offering people the right to freely distribute copies and modified versions of a work with the stipulation that the same rights be preserved in derivative works created later. Copyleft simple english wikipedia, the free encyclopedia. A very fast tutorial on open source licenses contact and coil. Highlights initial oss license choice is dependent on the level of oss developmental efforts.
The gnu general public license gpl is the principal copyleft license. Here you will find an archive of all the copyleft and open source licenses that have been published in the past. Users are permitted to engage in copying and distributing ed materials. A tale of two copyleft licenses while determining the proper methodology and criteria to yield an accurate count remains difficult, the gpl is generally considered one of the most widely used free software licenses. With law, authors have complete control over their materials. The license we use is the attributionsharealike license. Free software is software whose source code is freely available to anyone to use for any purpose, including studying, copying, modifying, extending and giving away. Copyleft is a term coined by the fsf and implies that if you distribute a derivative work of a work under a copyleft license, you must distribute the derivative under the same license as the original work it may however be combined with works under a permissive license that is deemed compatible, read on.
This license, the lesser general public license, applies to some specially designated software packagestypically librariesof the free software foundation and other authors who decide to use it. Jun 14, 2011 software licenses can be defined as permissive or copyleft. Its a piece of legal documentation created by the great people at creative commons that basically says the same thing as above. Copyleft compliance projects software freedom conservancy. Note that it is a copyleft license, unlike the nearly identical academic free license made by the same author. Ultimately, rms was the primary author of gplv3, but he listened to feedback from all sorts of individuals and even for profit companies. Ultimately, rms was the primary author of gplv3, but he listened to feedback from all sorts of individuals and even forprofit companies. Noncommercial nc creative commons cc software copy license scl general public license. Under most conditions, semirestrictive licenses will be preferred to the extremes. According to this gnu project page, regarding microsoft public license mspl. The trade in used licences is based on a very simple principle.
For unique licensing applications regarding logical partitions, see software licensing for ibm licensed programs on logical partitions. It is an example of a powerful copyleft license that requires derived works to be available under the same copyleft. The results suggest that leastrestrictive or noncopyleft license will dominate other types of oss license when a large effort is required to develop derivative software. These limitations may include restricting the use of the software to certain machines, a specified numbers of users, internal business purposes and the like. The free software component does not allow some exception to strong copyleft i. Software licenses can be defined as permissive or copyleft. Whats the difference between permissive and copyleft. May 23, 2011 weak copyleft, on the other hand, means that when software contains some of your code, some parts of the software must be distributed under your licence, if the software is distributed at all. Businesses use copyleft licenses to protect their software and different benefits within them from other companies essentially making the same type of software. Copyleft is a distinguishing feature of some free software licenses.
For a general description of how software license keys are used, see the topic working with software agreements and licenses. The precise terms and conditions for copying, distribution and. The most wellknown free software license that uses strong copyleft is the gnu general public license. There is an ongoing debate as to which class of license provides the greater degree of freedom. Question 30 points 10 out of 10 software can be legally. The principles of communityoriented gpl enforcement. Under fair use, however, the copyleft license may be superseded, just like. This general public license is the most widely used type of free software license, and was originally created for the gnu project by richard stallman. Optimal license choice not necessarily the preferred license of the oss. The freedom to modify and improve is somewhat empty without the freedom to share those. How existing gpld software can be used in existing enterprises. Many freesoftware licenses are not copyleft licenses because they do not require the licensee to distribute derivative works under the same license.
There is no one measurement of the state of copyleft. General public licenses are a popular copyleft license used in software. The latter removes the right to add further license restrictions upon redistribution. Some of the open source licenses use license agreements in the opposite manner to minimize or eliminate restrictions on users. States should not allow patents to restrict development and use of software on generalpurpose computers, but in those that do, we wish to avoid the special.
Jun 24, 2006 most copylefted software is issued under the gnu general public license gpl, which was the first copyleft license and by far the most commonly used license for free software. If a license is not copyleft, but it is foss, the user may depending on the exact terms of the license, be able to release binaryonly copies of the software, with limited distribution e. Copyleft software licenses are considered protective or reciprocal, as. Ssrn copyleft, the disguised copyright papers in the ssrn. Copyleft enables volunteer programmers and organizations to feel involved and contribute to software and feel confident any future derivatives will remain accessible to them, and that their contributions are part of a larger goal, like developing the kernel of an operating system os. Copyleft is free software license requiring authors to permit some of their work to be reproduced. What is a popular copyleft license used for software. Gpl version 3 this chapter discusses the text of gplv3. Bsd license problem gnu project free software foundation. A stronger copyleft license is the agpl which requires the publishing of the source code also for the usage case software as a service, see also the term sometimes used, service as a software substitute saass 30 31 32 e. Greater the efforts to develop the oss, less likely that its license is restrictive.
Much widely used code is released under copyleft licenses, especially the gpl, but much is also released under non copyleft licenses. Copyleft is a framework that permits ongoing sharing of a published work, with clear permissions that both grant and defend its users freedoms in contrast to other free licenses that grant freedom but dont defend. The licenses for most software and other practical works are designed to take away your freedom to share and change the works. Understanding the copyright license smashing magazine. This license is only applicable with earlier versions of apache software.
You may not link against third party closed source software. According to the software industry, the decision paved the way for piracy of material through web pages and other commonly used internet sites. You can use, modify and distribute the license under the same or equivalent license, but you should also share the source code. Copyleft definition of copyleft by the free dictionary. After opting into the copyleft licence, the source code is readily available, and it allows others to modify and develop the code.