GPL

GPL
source
Name	GNU General Public License
Version	3.0
Author	Richard Stallman
Publisher	Free Software Foundation
Published	25 February 1989
Dfdg	compatible
Website	https://www.gnu.org/licenses/gpl.html

GPL. The GNU General Public License is a widely used free software license that guarantees end users the freedom to run, study, share, and modify the software. Originally written by Richard Stallman for the GNU Project, it was the first copyleft license for general use, ensuring that all derivative works remain free under the same terms. Its legal and philosophical framework has profoundly shaped the open-source software movement and remains a cornerstone of software freedom.

Overview

The license is designed to prevent the software from becoming proprietary, a principle known as copyleft, which uses copyright law to enforce freedom rather than restrict it. It applies to the source code and any derivative work, requiring that the same freedoms be preserved in subsequent distributions. This legal mechanism ensures that contributions to projects like the Linux kernel and the GNU Compiler Collection remain perpetually accessible to the community. The philosophy underpinning it is formally articulated in the GNU Manifesto and is a central tenet of the free software movement.

History and development

The first version was drafted by Richard Stallman in 1989 with legal advice from Eben Moglen, aiming to protect the software of the GNU Project from proprietary appropriation. Version 2, released in 1991, became particularly famous as the license for the Linux kernel, creating the foundational combination known as GNU/Linux. The lengthy process to develop version 3 began in 2005, involving extensive public consultations and debates within communities like Debian and the Electronic Frontier Foundation, and was finally published by the Free Software Foundation in 2007 to address issues like tivoization and software patents.

Terms and conditions

The core requirements mandate that anyone who redistributes the software, with or without modifications, must provide recipients access to the complete corresponding source code. It also requires that the license itself and a copy of the notice of warranty be included with all copies. These terms are activated upon conveyance, meaning the obligations apply not to private use but to the act of distribution, whether commercially or not. Key clauses are designed to uphold the four essential freedoms defined by the Free Software Foundation.

Versions and variants

The three main versions are historically distinct, with version 2 remaining extremely popular for projects like the Linux kernel. Version 3 introduced stronger protections against hardware restrictions and clarified compatibility with other licenses like the Apache License. The family also includes several variants, such as the GNU Lesser General Public License (LGPL) for library code and the GNU Affero General Public License (AGPL) designed for network server software. Each variant adjusts the copyleft conditions for different use cases while maintaining the core philosophical goals.

Compatibility with other licenses

Compatibility is a complex legal issue, as the strong copyleft terms can conflict with the conditions of other free software licenses. It is generally compatible with permissive licenses like the MIT License and the BSD licenses, as their terms can be subsumed. However, merging code with licenses that have additional restrictions, such as the original BSD license's advertising clause, creates incompatibility. The Free Software Foundation maintains a detailed list of license compatibilities, and version 3 was specifically drafted to improve interoperability with licenses like the Eclipse Public License.

Reception and impact

It has received both praise and criticism, hailed by advocates like Linus Torvalds for protecting community software but sometimes criticized by corporations for its restrictive nature. Its influence is immense, serving as the legal foundation for critical infrastructure including the Linux kernel, WordPress, and Git. The license has also sparked significant legal discussions and enforcement actions, notably by organizations like the Software Freedom Law Center. Its principles have extended beyond software, inspiring similar licenses for creative works and hardware designs, cementing its role in the broader free culture movement.

Category:Free software licenses Category:1989 software Category:GNU Project