The Artistic License is an open-source license used for certain free and open-source software packages, most notably the standard implementation of the Perl programming language and most CPAN modules, which are dual-licensed under the Artistic License and the GNU General Public License (GPL).
Free software, libre software, or libreware 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.
The MIT License is a permissive software license originating at the Massachusetts Institute of Technology (MIT) in the late 1980s. As a permissive license, it puts very few restrictions on reuse and therefore has high license compatibility.
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 Mutopia Project is a volunteer-run effort to create a library of free content sheet music, in a way similar to Project Gutenberg's library of public domain books. It started in 2000.
Open Library is an online project intended to create "one web page for every book ever published". Created by Aaron Swartz, Brewster Kahle, Alexis Rossi, Anand Chitipothu, and Rebecca Malamud, Open Library is a project of the Internet Archive, a nonprofit organization. It has been funded in part by grants from the California State Library and the Kahle/Austin Foundation. Open Library provides online digital copies in multiple formats, created from images of many public domain, out-of-print, and in-print books.
William Mundy was a Renaissance English composer of sacred music and father of composer John Mundy. Over four hundred years after his death, William Mundy's music is still performed and recorded.
The WTFPL is a permissive free software license. As a public domain like license, the WTFPL is essentially the same as dedication to the public domain. It allows redistribution and modification of the work under any terms. The name is an abbreviation of Do What The Fuck You Want To Public License.
The International Music Score Library Project (IMSLP), also known as the Petrucci Music Library after publisher Ottaviano Petrucci, is a subscription-based digital library of public-domain music scores. The project uses MediaWiki software, and as of 24 November 2023 has uploaded more than 736,000 scores and 80,700 recordings by 1,900 performers of more than 226,000 works by 27,400 composers. IMSLP has both an iOS app and an Android app.
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.
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.
BSD licenses are a family of permissive free software licenses, imposing minimal restrictions on the use and distribution of covered software. This is in contrast to copyleft licenses, which have share-alike requirements. The original BSD license was used for its namesake, the Berkeley Software Distribution (BSD), a Unix-like operating system. The original version has since been revised, and its descendants are referred to as modified BSD licenses.
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 General Public License is a series of widely used free software licenses, or copyleft, that guarantee end users the four freedoms to run, study, share, and modify the software. The license was the first copyleft for general use and was originally written by Richard Stallman, the founder of the Free Software Foundation (FSF), for the GNU Project. The license grants the recipients of a computer program the rights of the Free Software Definition. The licenses in the GPL series are all copyleft licenses, which means that any derivative work must be distributed under the same or equivalent license terms. It is more restrictive than the Lesser General Public License and even further distinct from the more widely-used permissive software licenses such as BSD, MIT, and Apache.
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.
XZ Utils is a set of free software command-line lossless data compressors, including the programs lzma and xz, for Unix-like operating systems and, from version 5.0 onwards, Microsoft Windows. For compression/decompression the Lempel–Ziv–Markov chain algorithm (LZMA) is used. XZ Utils started as a Unix port of Igor Pavlov's LZMA-SDK that has been adapted to fit seamlessly into Unix environments and their usual structure and behavior.
Software categories are groups of software. They allow software to be understood in terms of those categories, instead of the particularities of each package. Different classification schemes consider different aspects of software.
Software Package Data Exchange (SPDX) is an open standard for software bills of materials (SBOMs). SPDX allows the expression of components, licenses, copyrights, security references and other metadata relating to software. Its original purpose was to improve license compliance, and it has since been expanded to facilitate additional use cases such as supply-chain transparency and security. SPDX is authored by the community-driven SPDX Project under the auspices of the Linux Foundation.
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.
