Free license. 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.

History 

The invention of the term "free license" and the focus on the rights of users were connected to the sharing traditions of the hacker culture of the 1970s public domain software ecosystem, the social and political free software movement (since 1980) and the open source movement (since the 1990s). These rights were codified by different groups and organizations for different domains in Free Software Definition, Open Source Definition, Debian Free Software Guidelines, Definition of Free Cultural Works and The Open Definition. These definitions were then transformed into licenses, using the copyright as legal mechanism. Ideas of free/open licenses have since spread into different spheres of society.

Open source, free culture (unified as free and open-source movement), anticopyright, Wikimedia Foundation projects, public domain advocacy groups and pirate parties are connected with free and open licenses.

Free software license

Free software licenses, also known as open-source licenses, are software licenses that allow content to be used, modified, and shared. They facilitate free and open-source software (FOSS) development. Intellectual property (IP) laws restrict the modification and sharing of creative works. Free and open-source licenses use these existing legal structures for an inverse purpose. They grant the recipient the rights to use the software, examine the source code, modify it, and distribute the modifications. These criteria are outlined in the Open Source Definition and The Free Software Definition.

After 1980, the United States began to treat software as a literary work covered by copyright law. Richard Stallman founded the free software movement in response to the rise of proprietary software. The term "open source" was used by the Open Source Initiative (OSI), founded by free software developers Bruce Perens and Eric S. Raymond. "Open source" is alternative label that emphasizes the strengths of the open development model rather than software freedoms. While the goals behind the terms are different, open-source licenses and free software licenses describe the same type of licenses.

The two main categories of free and open-source licenses are permissive and copyleft. Both grant permission to change and distribute software. Typically, they require attribution and disclaim liability. Permissive licenses come from academia. Copyleft licenses come from the free software movement. Copyleft licenses require derivative works to be distributed with the source code and under a similar license. Since the mid-2000s, courts in multiple countries have upheld the terms of both types of license. Software developers have filed cases as copyright infringement and as breaches of contract.

Free content license

According to the current definition of open content on the OpenContent website, any general, royalty-free copyright license would qualify as an open license because it 'provides users with the right to make more kinds of uses than those normally permitted under the law. These permissions are granted to users free of charge.' However, the narrower definition used in the Open Definition effectively limits open content to libre content. Any free content license, defined by the Definition of Free Cultural Works, would qualify as an open content license.

Licenses

By type of license 
 Public domain licenses
 Creative Commons CC0
 WTFPL
 Unlicense
 Public Domain Dedication and License (PDDL)
 Permissive licenses
 Apache License
 BSD License
 MIT License
 Mozilla Public License (file-based permissive copyleft)
 Creative Commons Attribution
 Copyleft & patentleft licenses
 GNU GPL, LGPL (weaker copyleft), AGPL (stronger copyleft)
 Creative Commons Attribution Share-Alike
 Mozilla Public License
 Common Development and Distribution License
 GFDL (without invariant sections)
 Free Art License

By type of content 
 Open-source software
 The Open Source Definition
 Open Content
 Open Content License
 Open Publication License
 Open-source hardware
 Open database
 Creative Commons v4
 Open Database Licence

By authors 
 Creative Commons
 Free Software Foundation
 Open Source Initiative
 Microsoft
 Microsoft Public License
 Microsoft Reciprocal License
 Open Content Project
 Open Data Commons from Open Knowledge Foundation
 Public Domain Dedication and License (PDDL)
 Attribution License (ODC-By)
 Open Database License (ODC-ODbL)
European Union
European Union Public Licence

See also 
 License compatibility
 License proliferation

Notes

References

External links 
 Open software licenses
 Open licenses
 Various Licenses and Comments about Them – GNU Project – Free Software Foundation
 Licenses - Definition of Free Cultural Works
 proposed Open Source Hardware (OSHW) Statement of Principles and Definition v1.0

Free and open-source software licenses
Contract law
Computer law
Copyright licenses
Terms of service
Open-source hardware
Patent law