Free software, libre software, libreware or rarely known as freedom-respecting software is computer software distributed under terms that allow users to run the software for any purpose as well as to study, change, and distribute it and any adapted versions. Free software is a matter of liberty, not price; all users are legally free to do what they want with their copies of a free software regardless of how much is paid to obtain the program. Computer programs are deemed "free" if they give end-users ultimate control over the software and, subsequently, over their devices.
Free music or libre music is music that, like free software, can freely be copied, distributed and modified for any purpose. Thus free music is either in the public domain or licensed under a free license by the artist or copyright holder themselves, often as a method of promotion. It does not mean that there should be no fee involved. The word free refers to freedom, not to price.
The Open Publication License (OPL) was published by the Open Content Project in 1999 as a public copyright license for documents. It superseded the Open Content License, which was published by the Open Content Project in 1998. Starting around 2002–2003, it began to be superseded, in turn, by the Creative Commons licenses.
A Creative Commons (CC) license is one of several public copyright licenses that enable the free distribution of an otherwise copyrighted "work". A CC license is used when an author wants to give other people the right to share, use, and build upon a work that the author has created. CC provides an author flexibility and protects the people who use or redistribute an author's work from concerns of copyright infringement as long as they abide by the conditions that are specified in the license by which the author distributes the work.
Share-alike (🄎) is a copyright licensing term, originally used by the Creative Commons project, to describe works or licenses that require copies or adaptations of the work to be released under the same or similar license as the original. Copyleft licenses are free content or free software licenses with a share-alike condition.
The free-culture movement is a social movement that promotes the freedom to distribute and modify the creative works of others in the form of free content or open content without compensation to, or the consent of, the work's original creators, by using the Internet and other forms of media.
A permissive software license, sometimes also called BSD-like or BSD-style license, is a free-software license which instead of copyleft protections, carries only minimal restrictions on how the software can be used, modified, and redistributed, usually including a warranty disclaimer. Examples include the GNU All-permissive License, MIT License, BSD licenses, Apple Public Source License and Apache license. As of 2016, the most popular free-software license is the permissive MIT license.
This comparison only covers software licenses which have a linked Wikipedia article for details and which are approved by at least one of the following expert groups: the Free Software Foundation, the Open Source Initiative, the Debian Project and the Fedora Project. For a list of licenses not specifically intended for software, see List of free-content licences.
The commercialization of copylefted works differs from proprietary works. The economic focus tends to be on the commercialization of other scarcities, and complimentary goods rather than the free works themselves. One way to make money with copylefted works is to sell consultancy and support to the users of the work. Generally, financial profit is expected to be much lower in a business model utilising copyleft works only than in a business using proprietary works. Another way is to use the copylefted work as a commodity tool or component to provide a service or product. Android phones, for example, include the Linux kernel, which is copylefted. Unlike business models which commercialize copylefted works only, businesses which deal with proprietary products can make money by exclusive sales, single and transferable ownership, and litigation rights over the work, although some view these methods as monopolistic and unethical, such as those in the Free Software Movement and the Free Culture Movement.
License compatibility is a legal framework that allows for pieces of software with different software licenses to be distributed together. The need for such a framework arises because the different licenses can contain contradictory requirements, rendering it impossible to legally combine source code from separately-licensed software in order to create and publish a new program. Proprietary licenses are generally program-specific and incompatible; authors must negotiate to combine code. Copyleft licenses are commonly deliberately incompatible with proprietary licenses, in order to prevent copyleft software from being re-licensed under a proprietary license, turning it into proprietary software. Many copyleft licenses explicitly allow relicensing under some other copyleft licenses. Permissive licenses are compatible with everything, including proprietary licenses; there is thus no guarantee that all derived works will remain under a permissive license.
Free content, libre content, libre information, or free information is any kind of creative work, such as a work of art, a book, a software program, or any other creative content for which there are very minimal copyright and other legal limitations on usage, modification and distribution. These are works or expressions which can be freely studied, applied, copied and modified by anyone for any purpose including, in some cases, commercial purposes. Free content encompasses all works in the public domain and also those copyrighted works whose licenses honor and uphold the definition of free cultural work.
A free-software license is a notice that grants the recipient of a piece of software extensive rights to modify and redistribute that software. These actions are usually prohibited by copyright law, but the rights-holder of a piece of software can remove these restrictions by accompanying the software with a software license which grants the recipient these rights. Software using such a license is free software as conferred by the copyright holder. Free-software licenses are applied to software in source code and also binary object-code form, as the copyright law recognizes both forms.
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, and similar approaches have even been applied to certain patents.
The GNU Free Documentation License is a copyleft license for free documentation, designed by the Free Software Foundation (FSF) for the GNU Project. It is similar to the GNU General Public License, giving readers the rights to copy, redistribute, and modify a work and requires all copies and derivatives to be available under the same license. Copies may also be sold commercially, but, if produced in larger quantities, the original document or source code must be made available to the work's recipient.
A Rights Expression Language or REL is a machine-processable language used to express intellectual property rights and other terms and conditions for use over content. RELs can be used as standalone expressions or within a DRM system.
The Definition of Free Cultural Works evaluates and recommends compatible free content licenses.
A free license or open license is a license that allows copyrighted work to be reused, modified, and redistributed. These uses are normally prohibited by copyright, patent or other Intellectual property (IP) laws. The term broadly covers free content licenses and open-source licenses, also known as free software licenses.
A public license or public copyright license is a license by which a copyright holder as licensor can grant additional copyright permissions to any and all persons in the general public as licensees. By applying a public license to a work, provided that the licensees obey the terms and conditions of the license, copyright holders give permission for others to copy or change their work in ways that would otherwise infringe copyright law.
Software relicensing is applied in open-source software development when software licenses of software modules are incompatible and are required to be compatible for a greater combined work. Licenses applied to software as copyrightable works, in source code as binary form, can contain contradictory clauses. These requirements can make it impossible to combine source code or content of several software works to create a new combined one.
