A copyleft license guarantees end users the freedom to run, study, share, or modify software, but with a critical condition: if you distribute a derivative work or modification, you must provide the source code to those recipients under the same or equivalent license terms. This ensures that the software remains free and open for all users.
Key Features of the GPL
The GPL includes several key features that define its approach to software freedom:
- Freedom to use: Users can run the software without restrictions.
- Freedom to study: With access to the source code, users can study how the software works and adapt it to their needs.
- Freedom to distribute: Users can redistribute copies of the software to others for free or a fee.
- Freedom to modify: Users can modify the software and distribute their modified versions, as long as they distribute the modified source code under the GPL.
Versions of the GPL
The GPL has evolved over time to address new challenges and clarify its terms:
- GPLv1: The original version, released in 1989.
- GPLv2: Released in 1991, with clarifications and additional terms.
- GPLv3: Released in 2007, with provisions to address software patents, digital rights management (DRM), and other issues.
Compliance and Legal Implications
When using GPL-licensed software in a project, it is essential to understand the implications of the license and ensure compliance with its terms to avoid legal issues. The GPL has played a significant role in the development of the open-source software movement and has influenced many other free software licenses.
