Copyleft
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.
Li-Chen Wang's Palo Alto Tiny BASIC for the Intel 8080 appeared in Dr. Dobb's Journal in May 1976.
Symbolics asked to use the Lisp interpreter, and Stallman agreed to supply them with a public domain version of his work.
This original GPL did not grant rights to the public at large, only those who had already received the program; but it was the best that could be done under existing law.
[11] In France, a series of meetings taking place in 2000 under the title "Copyleft Attitude" gave birth to the Free Art License (FAL),[12] theoretically valid in any jurisdiction bound by the Berne Convention and recommended by Stallman's own Free Software Foundation.
[13] Shortly thereafter, a separate, unrelated initiative in the United States yielded the Creative Commons license, available since 2001 in both permissive (BY) and copyleft (BY-SA) variants and more specifically tailored to U.S. law.
They ensure that rights cannot be later revoked, and require the work and its derivatives to be provided in a form that allows further modifications to be made.
Traditional copyright law is designed to promote progress by providing economic benefits to creators.
When choosing to copyleft their work, content creators may seek complementary benefits like recognition from their peers.
Some creators, such as Elastic,[16] feel that preventing commercial enterprises from using and then selling their product under a proprietary license is also an incentive.
Furthermore, the open-source culture of programming has been described as a gift economy, where social power is determined by an individual's contributions.
[23] Copyleft licenses necessarily make creative use of relevant rules and laws to enforce their provisions.
For example, in some countries, it is acceptable to sell a software product without warranty, in standard GNU General Public License style, while in most European countries it is not permitted for a software distributor to waive all warranties regarding a sold product.
This allows programs of any license to be compiled and linked against copylefted libraries such as glibc and then redistributed without any re-licensing required.
An even stronger copyleft license is the AGPL, which requires the publishing of the source code for software as a service use cases.
It has been suggested that copyleft has become a divisive issue in the ideological strife between the Open Source Initiative and the free software movement.
[47][48][49] Microsoft vice-president Craig Mundie remarked, "This viral aspect of the GPL poses a threat to the intellectual property of any organization making use of it.
"[50] In another context, Steve Ballmer declared that code released under GPL is useless to the commercial sector, since it can only be used if the resulting surrounding code is licensed under a GPL-compatible license, and described it thus as "a cancer that attaches itself in an intellectual property sense to everything it touches".
[51] In response to Microsoft's attacks on the GPL, several prominent free-software developers and advocates released a joint statement supporting the license.
[52] According to FSF compliance engineer David Turner, the term "viral license" creates a misunderstanding and a fear of using copylefted free software.
[54] David McGowan has also written that there is no reason to believe the GPL could force proprietary software to become free software, but could "try to enjoin the firm from distributing commercially a program that combined with the GPL'd code to form a derivative work, and to recover damages for infringement."
"[55] Richard Stallman has described this view with an analogy, saying, "The GPL's domain does not spread by proximity or contact, only by deliberate inclusion of GPL-covered code in your program.
"[56] Popular copyleft licenses, such as the GPL, have a clause allowing components to interact with non-copyleft components as long as the communication is abstract,[failed verification] such as executing a command-line tool with a set of switches or interacting with a web server.
[57] As a consequence, even if one module of an otherwise non-copyleft product is placed under the GPL, it may still be legal for other components to communicate with it in ways such as these.
[clarification needed] This allowed communication may or may not include reusing libraries or routines via dynamic linking – some commentators say it does,[58] the FSF asserts it does not and explicitly adds an exception allowing it in the license for the GNU Classpath re-implementation of the Java library.
On modern computer systems, the character U+1F12F 🄯 COPYLEFT SYMBOL can be generated using one of these methods (keyboard shortcuts):
