The first two sections provide a brief history of WordPress, its adoption of the GPL, and a summary of the license. These sections are a bit dry, but Chapter 3 is where it gets more interesting, particularly for theme and plugin developers who have questions about licensing GPL-derivatives. Best explores the practical application of the GPL in common business scenarios:
- If I modify the core WordPress software or a GPL’d theme or plugin, must I release the source code of the modified versions(s) to the public?
- I’m a theme/plugin developer. I’ve put huge effort into writing my theme/plugin and I’m going to release it under the GPL but I want to make sure that everyone who receives my theme or plugin, even if from someone else, is obliged to pay me a licensing fee or notify me that they have it. Can I do that?
- I’ve purchased some fully GPL’d themes or plugins from a commercial theme or plugin provider. May I sell those themes or plugins from my own website for my own benefit or publish those themes or plugins on my own website and give them away for free?
Subsequent chapters cover controversies surrounding “GPL non-compliant” sales models, applications of copyright law, GPL compatibility with other licenses, and trademarks. Both the audio and the PDF ebook are available for download on Best’s website. The text of the book is licensed under the Creative Commons Attribution 4.0 International License.