GNU General Public License

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GNU General Public License

Author	Richard Stallman
Latest version	3
Publisher	Free Software Foundation
Published	25 February 1989; 35 years ago (1989-02-25)
SPDX identifier	GPL-3.0-or-later GPL-3.0-only GPL-2.0-or-later GPL-2.0-only GPL-1.0-or-later GPL-1.0-only
Debian FSG compatible	Yes[1]
FSF approved	Yes[2]
OSI approved	Yes (applies to GPLv3-only and GPLv2-only)[3]
Copyleft	Yes[2][4][5]
Linking from code with a different licence	Software licensed under GPL compatible licenses only, with the exception of the LGPL which allows all programs.[6]
Website	www.gnu.org/licenses/gpl.html

The GNU General Public Licenses (GNU GPL, or simply GPL) are a series of widely used free software licenses, or copyleft licenses, that guarantee end users the freedoms to run, study, share, and/or modify the software.^[7] The GPL was the first copyleft license available for general use. It was originally written by Richard Stallman, the founder of the Free Software Foundation (FSF), for the GNU Project. The license grants the recipients of a computer program the rights of the Free Software Definition.^[8] The licenses in the GPL series are all copyleft licenses, which means that any derivative work must be distributed under the same or equivalent license terms. It is more restrictive than the Lesser General Public License, and even further distinct from the more widely-used permissive software licenses such as BSD, MIT, and Apache.

Historically, the GPL license family has been one of the most popular software licenses in the free and open-source software (FOSS) domain.^{[7][9][10][11][12]} Prominent free software programs licensed under the GPL include the Linux kernel and the GNU Compiler Collection (GCC). David A. Wheeler argues that the copyleft provided by the GPL was crucial to the success of Linux-based systems, giving the programmers who contributed to the kernel assurance that their work would benefit the whole world and remain free, rather than being exploited by software companies that would not have to give anything back to the community.^[13]

In 2007, the third version of the license (GPLv3) was released to address some perceived problems with the second version (GPLv2) which were discovered during the latter's long-time usage.

To keep the license current, the GPL license includes an optional "any later version" clause, allowing users to choose between the original terms or the terms in new versions as updated by the FSF. Software projects licensed with the optional "or later" clause include the GNU Project, while projects like the Linux kernel is licensed under GPLv2 only.

The "or any later version" clause is sometimes known as a "lifeboat clause" since it allows combinations between different versions of GPL-licensed software to maintain compatibility.