| Revision as of 12:11, 2 June 2003 edit203.220.12.107 (talk) Viral nature of copyright. From public domain to copyleft.← Previous edit | Revision as of 12:16, 2 June 2003 edit undo203.220.12.107 (talk) Minor editingNext edit → | ||
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| Copyleft licenses are sometimes called '''viral copyright licenses''' because any works derived from a copylefted work must themselves be copylefted. However, ] itself is a viral license, since any works derived from a copyrighted work must have permission and be under conditions set by the copyright holder. | Copyleft licenses are sometimes called '''viral copyright licenses''' because any works derived from a copylefted work must themselves be copylefted. However, ] itself is a viral license, since any works derived from a copyrighted work must have permission and be under conditions set by the copyright holder. | ||
| The concept of non-copyright rights has moved from the weak ] model to the copyleft license with ] equal to copyright. Previously, copyright could incorporate any public domain material, but the public domain could not similarly incorporate any copyrighted property. Copyleft removes this inequality. | |||
| The term '''viral copyright licenses''' is considered derogatory, as it compares copylefted works to harmful ]es. However, the analogy between copyleft and computer viruses is not close; as advocates of copyleft point out, computer viruses infects computers without the awareness of the user, whereas the copyleft actually grants the user certain permissions to distribute modified programs, which is otherwise not allowed under copyright law, and under most proprietary licenses. | The term '''viral copyright licenses''' is considered derogatory, as it compares copylefted works to harmful ]es. However, the analogy between copyleft and computer viruses is not close; as advocates of copyleft point out, computer viruses infects computers without the awareness of the user, whereas the copyleft actually grants the user certain permissions to distribute modified programs, which is otherwise not allowed under copyright law, and under most proprietary licenses. | ||
Revision as of 12:16, 2 June 2003
Copyleft refers to a concept invented by Richard Stallman of the Free Software Foundation in 1984: the application of copyright laws to ensure uncompromised public freedom to manipulate, improve, and redistribute specific information and all its derivative works. Initially only designed for software distribution, the concept is now also being used for other types of material.
In copyleft, the copyright holder grants an irrevocable license to the recipient of a copy, permitting the redistribution (including sale) of possibly modified further copies, under the condition that all those copies carry the same license and are made available in a form which facilitates modification.
Some other free software licenses as well as so-called open source licenses, such as those used by BSD and the X Window System, are not copyleft licenses because they do not extend to derivative works and include no requirement to make source code available. It is a matter of debate whether these licenses provide a larger or smaller degree of freedom than copyleft licenses. While the former licenses attempt to maximize the freedom of the initial recipient, the latter licenses try to maximize the freedom of all potential recipients in the future.
Copyleft licenses are sometimes called viral copyright licenses because any works derived from a copylefted work must themselves be copylefted. However, copyright itself is a viral license, since any works derived from a copyrighted work must have permission and be under conditions set by the copyright holder.
The concept of non-copyright rights has moved from the weak public domain model to the copyleft license with power equal to copyright. Previously, copyright could incorporate any public domain material, but the public domain could not similarly incorporate any copyrighted property. Copyleft removes this inequality.
The term viral copyright licenses is considered derogatory, as it compares copylefted works to harmful computer viruses. However, the analogy between copyleft and computer viruses is not close; as advocates of copyleft point out, computer viruses infects computers without the awareness of the user, whereas the copyleft actually grants the user certain permissions to distribute modified programs, which is otherwise not allowed under copyright law, and under most proprietary licenses.
The concept of copyleft arose when Stallman was working on a LISP interpreter. Symbolics asked to use the LISP interpreter, and Stallman agreed to supply them with a public domain version of his work. Symbolics extended and improved the LISP interpreter, but when Stallman wanted access to the improvements that Symbolics had made to his interpreter, Symbolics refused. Stallman then proceeded to create a software license that would prevent this behavior.
The term "Copyleft" comes from the phrase "Copyleft--all rights reversed", which Don Hopkins wrote in a message to Stallman in 1984 and which is intended as a double pun on the phrase "Copyright--all rights reserved".
Free software licenses which are examples of copyleft licenses include the GNU General Public License, the GNU Lesser General Public License, the Mozilla Public License, and the Q Public License. Copyleft licenses for materials other than software include the Open Content License, and the GNU Free Documentation License. The latter is being used for the content of Misplaced Pages.
Copyleft-like ideas are increasingly being suggested for patents, such as open patent pools that allow royalty-free use of patents contributed to the pool under certain conditions (such as surrendering the right to apply for new patents that are not contributed to the pool).