The file wp-includes/gpl-license.txt in WordPress installations contains the full text of the GNU General Public License (GPL) version 2, which is the license under which WordPress is distributed. Here is detailed information about this file:
The gpl-license.txt file includes the entire GPLv2 license text. This license outlines the terms under which the software can be copied, distributed, and modified. WordPress, being open-source software, uses this license to ensure that:
WordPress has been released under the GPL since its inception in 2003. The GPL was chosen by WordPress's co-founder Matt Mullenweg because it aligns with the project's philosophy of open source software development, promoting collaboration and freedom of use, modification, and distribution.
Over the years, there have been discussions within the WordPress community about whether WordPress should move to a newer version of the GPL or use a different license. However, the decision to stick with GPLv2 has been to maintain compatibility with a wide range of software that might still use this version of the license. For instance, discussions around this topic can be found in the WordPress core development blog.
The GPL has implications for how WordPress can be used commercially. For example, companies that modify WordPress must make those modifications available under the same license. This aspect has led to various legal interpretations and court cases, influencing how businesses operate with open-source software. For detailed legal insights, resources like the GNU GPL FAQ provide extensive information.
The wp-includes/gpl-license.txt file is not just a legal document but a testament to WordPress's commitment to the principles of free and open-source software. It serves as a reminder of the freedoms granted to users and developers alike, fostering an environment where innovation can thrive under a shared set of ethical guidelines.