FOSS Licensing/Glossary

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This section is a derivative work of its Mandarin version co-authored by Rong-chi Chang and Chingyuan Huang, former colleagues of the OSSF, Institution of Information Science, Academia Sinica.

Proposed by free software advocates, copyleft is an alternative framework conceived within copyright law which usually confers exclusive rights to copyright holders and thus limits access to the work by all others. Authors may want to “copyleft” their works to grant certain rights to people who are interested in distributing or modifying their works, provided these people will also “copyleft” all the derivative works. Although copyright and copyleft might represent very different ideas regarding the relationship between authors and their works, copyleft is not against copyright law. On the contrary, without the rights granted by the copyright law, authors will not have the power to copyleft their works. Please also refer also to the definition provided by the Free Software Foundation at .
A bundle of rights regarding the use of a creative expression (including literary works, music compositions, movies, paintings, software, and the like) that the law grants exclusively to the author. Copyright is applied to a work upon its creation. Except for the limitation set by copyright law, any use of a work without the copyright holder’s consent is regarded as an infringement. Note that copyright law protects only the expression of ideas but not the ideas themselves.
Copyright Holder
The individual or legal entity who is entitled to exclusive rights under copyright law. It is usually said that copyright law aims to protect authors of creative works. But since most of the rights protected are treated as property rights and may be transferred, many copyright holders are not the authors of the works themselves but their employers or those who have commissioned these works.
Derivative Work
Copyright law is applied to every work once it is created. With the consent of the copyright holder, one can use this (original) work to create derivative works. For example, a newer version of a program might contain all or part of the code of the earlier version. Thus the newer version is a derivative work of the earlier version. Translation of a document is also regarded as a type of derivative work.
Distribution of the copies of a work is also an exclusive right granted to the copyright holder. In FOSS licenses, all receivers of copies of a program are allowed to make further distributions. The term redistribution may be used when emphasizing that the distributor has received the program from somewhere and is distributing further.
Fair Use
Copyright law seeks to maintain a balance between private and public interests. “Fair use” is developed to limit excessive copyright protection and to allow the general public greater access to copyrighted works. When a work is used without the consent of the copyright holder for purposes of criticism, comments, news reporting, teaching, scholarship or research, such use might not be considered an infringement. Though copyright may differ in different jurisdictions, usually the following factors are considered by the court in deciding whether a case falls under fair use or is an infringement:
  • The purpose and character of the use, including whether such use is of a commercial nature or is for non-profit educational purposes.
  • The nature of the copyrighted work.
  • The amount and substantiality of the portion used in relation to the copyrighted work as a whole.
  • The effect of the use upon the potential market for or value of the copyrighted work.
First-sale Doctrine
The first-sale doctrine is an exception of copyright law that is codified in Section 109 of the US Copyright Act. Similar doctrines may be also be adopted by other countries. The doctrine allows the person who purchased a legally acquired copy of a copyrighted work to further distribute (including sell, rent or give away) the copy without permission from the copyright holder. But the first-sale doctrine does not apply to phono-records and computer software.
A license is a legal document that copyright holders may adopt to regulate how people can use their works. Users are often required to accept the terms and conditions of a license as a prerequisite to their use of the copyrighted works.
Multiple Licensing
The copyright holder of a work can have various ways of making use of his/her work available to others. The terms and conditions she would want users to accept may differ from case to case. For example, the copyright holder of an editor software may be willing to issue an academic license that is cheaper and more affordable for students, while commercial licenses are adopted when the program is sold to commercial entities. A copyright holder can also decide to license a work under both FOSS licenses and proprietary licenses to achieve different purposes.
Public Domain
The term public domain is used to describe all creative works that are not protected by copyright law and can therefore be used freely. Works that are in the public domain might be cultural heritage that came to existence before copyright law, or works that were once protected but whose copyright has expired, or works for which their copyright holder decides not to claim copyright. In the latter case, the disclaimer must be made explicitly. In some countries, a signed written document deposited with a national registrar may even be required. Works that are licensed under FOSS licenses are still copyrighted and do not fall into this category.
Source Code
Source code is written in special kinds of languages designed for programming. A program in its source code form might not be easy for lay people to understand, but it is comprehensible to trained programmers. When the source code is converted to machine readable form, even programmers will have difficulty understanding and modifying the program. Therefore, access to the source code is a prerequisite for the development of FOSS and a principle embraced in all FOSS licenses. A more detailed explanation of “source code” can be found in the Glossary of the introductory primer, Free/Open Source Software, A General Introduction, which is available online at
When a copyright holder licenses her work to someone else, she can also choose to allow the licensee to sublicense the work. That is, when the licensee distributes the work, within the scope of rights granted by the licensor, the licensee is not only a (re)distributor but also a licensor of a sub-license between her and the other party (licensee of a sub-license). However, most FOSS licenses do not grant people the right to sub-license. For example, A is the copyright holder of X program. B receives a copy of X and distributes more copies. C receives the copy from B. If A does not grant B the right to sub-license, both B and C receive the license directly from A. If A grants the right B to sub-license program X, within the scope of the rights granted by A, B may start a new license and him/herself become a (sub)licensor of program X.
Warranty Disclaimer
Warranty is a guarantee made by the vendor against potential liabilities arising from the use of a product. All FOSS licenses come with a warranty disclaimer. Such clauses are designed to protect the author of FOSS programs, for these programs are licensed without royalty and changes might be added in its development. However, although FOSS programs themselves are royalty-free and disclaim warranty, vendors of FOSS programs can always provide their customers with a warranty and various kinds of supports for a fee.
Another reason why licenses of community distributions may not include warranty clauses may be because developers are expected to understand the code and fix the bugs, and are invited and expected to take on some responsibility as a member of the community. However, in commercial distribution, it is unreasonable to expect customers to be capable to read and change the code. In some countries, failure to provide minimum guarantee will lead to consumer protection issues