The GNU General Public License is a free, copyleft software license that preserves the users’ freedom to use, change, copy, and distribute software. Richard Stallman originally authored the GNU General Public License (GNU GPL or GPL) in 1989 with the goal of creating a single license to cover the software programs in the GNU project. Stallman wanted to create a license that guaranteed the four basic principles of free software and to protect the freedoms across all future releases. The GNU GPL implements a copyright approach termed copyleft, in which the GNU GPL is able to leverage the current copyright system’s rules to preserve the freedoms of all derived works. To adhere to the principles of copyleft licensing, the GNU GPL states that all derived work must be released under the same license. The primary goal of the GNU GPL is to ensure the free software will remain free (GNU Project, 2013).
Since its creation, the GNU GPL has undergone two major version updates. The first update was in 1991 with the release of version 2 when small changes were introduced to protect principles software freedom against software patents. This protection from patents has been referred to as the “Liberty and Death” clause, which states that if a patent is used to make a program non-free the program cannot be distributed. The second major change to the GNU GPL occurred in 2007 when it was updated to version 3. This updated added and refined the license ability to protect the software freedoms from newly emerged threats and existing exploited loopholes. The first change addressed digital right management (DRM) and its utilization of GNU GPL protected software. The issues regarding DRM originated with the use of GNU GPL licensed software within Tivo devices that restricted the freedom to modify and execute custom software changes. GNU GPLv3 now prohibits implementing proprietary control mechanisms that restrict the freedom to execute modified version of GNU GPL licensed software. The other change relating to DRM is that future users must be able to access all generated data through GNU GPLv3 license software. This protects against the use of encryption within the software, as any encryption keys must be made available to allow access to the generated data. The second area changed in version 3 dealt with the “Liberty of Death” clause, which was extended it to include an explicit patent grant. This was added to align the protection of the GNU GPL license across the different world patent systems (FSFE, 2013). The final major change in version 3 is the handling of compatible with other license types. This change allows GNU GPL licensed software to incorporate software code from other project with different licenses, like the XFree89 1.1 license and the Apache License 2.0 (GNU Project, 2013).
In conclusion, the GNU GPL has played a fundamental role in shaping how we view and utilize software. Since its creation, the GNU GPL has remained the most widely used license for free and open-source software, including many high profile projects like the Linux kernel, Blender, GIMP, Inkscape and Wordpress (BlackDuck, 2013). The driving goal behind the GNU GPL has remained the same to preserve the four basic freedoms of free software: The freedom to use a program for any purpose, the freedom to access and modify a program’s source, the freedom to copy and share a program, and the freedom to share a modified program.
BlackDuck (2013). Top 20 Open Source Licenses. Retrieved from http://www.blackducksoftware.com/resources/data/top-20-open-source-licenses
FSFE (2013). FSFE: Patents and GPLv3. Retrieved from https://fsfe.org/campaigns/gplv3/patents-and-gplv3.en.html#Explicit-patent-grant
GNU Project (2013). GNU Project: A Quick Guide to GPLv3. Retrieved from https://www.gnu.org/licenses/quick-guide-gplv3.html
GNU Project (2013). GNU Project: What is Copyleft? Retrieved from https://www.gnu.org/copyleft/copyleft.html
Silberschatz, A., Galvin, P., Gagne, G. (2012). Operating System Concepts, Eighth Edition, 38. Retrieved from http://users.suse.com/~agruen/acl/linux-acls/online/
Stallman, R (2006). FSFE: Transcript of Richard Stallman at the 2nd international GPLv3 conference. Retrieved from https://fsfe.org/campaigns/gplv3/fisl-rms-transcript.en.html#before-gnu-gpl