![]() ![]() The latest version, GNU GPL v3, was released in 2007. Since then, the GNU GPL has been updated several times. The original GNU General Public License (GNU GPL), which Stallman wrote in 1989 to accompany the GNU operating system and related programs, put the concept of copyleft into explicit form. That’s why we reverse the name, changing “copyright” into “copyleft.” ( GNU.org, “What is Copyleft?”) “Proprietary software developers use copyright to take away the users’ freedom we use copyright to guarantee their freedom. Thus, the code and the freedoms become legally inseparable. The “What is Copyleft?” page of GNU.org explains copyleft with regard to software in these terms: “To copyleft a program, we first state that it is copyrighted then we add distribution terms, which are a legal instrument that gives everyone the rights to use, modify, and redistribute the program's code, or any program derived from it, but only if the distribution terms are unchanged. Stallman built the GNU operating system with the above freedoms - and the concept of copyleft - in mind. The freedom to distribute an improved version and thus help build the community ![]() The freedom to change the program as you wish, by having full access to source codeĤ. The freedom to copy the program and give it away to your friends and co-workersģ. The freedom to run the program as you wishĢ. According to Stallman, a truly free software program would allow the following:ġ. Things got more serious in the 1980s when famed free software advocate Richard Stallman made the word the centerpiece of the GNU Project. And it positioned “free” (as in free to use, copy, modify, etc.) software (Tiny BASIC) against proprietary/copyrighted software (Microsoft’s Altair BASIC). ![]() That line didn’t have any legal power, but it was catchy (and pretty funny, if we do say so). Li-Chen Wang added this humorous text to the distribution notice of his Palo Alto Tiny BASIC programming language: "COPYLEFT ALL WRONGS RESERVED." The line was a dig at Microsoft co-founder Bill Gates, who had complained about software hobbyists pirating the company’s Altair BASIC program, which sold for $150 a pop at the time. The word “copyleft” was coined in direct opposition to the familiar term “copyright.” In 1976, developer Dr. In this blog, we’ll take a close look at copyleft licenses, including their history, how they compare to permissive licenses, and the difference between strong and weak copyleft licenses. ![]() For developers of free and open source software, copyleft is a way to ensure the software remains freely available. For developers of proprietary software, software under copyleft licenses must be used with care. That is a feature or a bug, depending on how you look at it. They also don’t have any such code-sharing requirement, so the “open source-ness” does not necessarily persist to the derivative work. One of the practical ramifications of this requirement is that OSS users may be forced to publish their own changes or additions in source code form if they release a binary that includes a copyleft-licensed component.Ĭopyleft licenses stand in contrast to permissive licenses, which tend to have few restrictions on use of the licensed code. In other words, the modified code has to be exactly as “open” as the original. GPL v2).īroadly, though, OSS licenses can be broken down into two categories: permissive and copyleft.Ĭopyleft licenses - the subject of this blog - generally require that any derivative work of the copyleft-licensed software be released under the same license as the original software. the Beerware License) to the classic (i.e. There are hundreds of different open source software licenses in use today, with provisions ranging from the comical (i.e. ![]()
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