An open-source license is a copyright license, originally born for computer software, that makes the source code available for everyone to use.
Open-source licenses are also commonly free, allowing for modification, redistribution, and commercial use without having to pay the original author.
Some open-source licenses only permit modification of the source code for personal use or only permit non-commercial redistribution.
Under Copyleft definition exists a form of licensing that can be used to maintain copyright conditions for works such as computer software, hardware, documents, art etc.
While copyright law gives software authors control over copying, distribution and modification of their works, the goal of copyleft is to give all users of the software the freedom to carry out these activities.
So the copyleft licenses are a novel use of existing copyright law, to ensure a work remains freely available.
Around derived works’ point of view, there is an ongoing debate for deciding what is the better choice is, in order to leave the software really free.
Free Software Foundation (FSF) licences impose that all kinds of derived works inherit the original copyleft license (“strong” copyleft); on the other hand, the Open Source Initiative (OSI) allows people to choose the licenses they prefer for their derived works (“weak” copyleft).
Some “strong” copyleft licenses:
– GNU General Public License (GPL), originally written by Richard Stallman, was the first copyleft license to see extensive use and continues to dominate the licensing of copylefted software.
Some applications: GNU/Linux operating system
– GNU Free Documentation License (GFDL), license for free documentation, designed by the Free Software Foundation (FSF) for the GNU Project. It gives readers the rights to copy, redistribute, and modify a work and requires all copies and derivatives to be available under the same license.
Some “weak” copyleft licenses:
– GNU Lesser General Public License (LGPL), published by the Free Software Foundation (FSF) in 1991. It was designed as a compromise between the “strong” copyleft GNU General Public License (GPL) and permissive licenses such as the BSD licenses and the MIT License.
Open-source licensing in creative fields
Open-source licensing in art is a way to share artworks over the internet, with controls set by the creator of the art. It allows the art to be recreated or rearranged by new artists, while still giving credit to the original creator. Websites like creativecommons.org give artists ways to open licenses to their work and make it available to the public (“partial” copyleft).
– Creative Commons (CC) is a non-profit organization founded in 2001 by Lawrence Lessig that provides a form of license condition called “ShareAlike”.
The licenses differ by several combinations that condition the terms of distribution.
Some applications: Arduino, Deviantart, Wikipedia.
– Free Art License, published in 2007 by Copyleft Attitude, grants the right to freely copy, distribute, and transform creative works without needing the author’s explicit permission. This license is an example of “weak” copyleft.
[Main source: wikipedia]
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