The GNU General Public License, GPL for short, is a copyleft license for open-source software products. It guarantees that the software under it can be freely used, modified, and distributed.
Under GPL licensing, software belongs to the public so that any creator or developer can access the original source code and build upon it to create new programs and products. Popular products under this license include WordPress.org, Linux kernel, and HTTPS Everywhere.
It’s the complete opposite of permissive licenses, which lets developers modify the original software and release it as a proprietary or closed-source product.
Why the GPL?
GPL was first written by Richard Stallman and the Free Software Foundation (FSF) in 1989. The intent was to have a general public license that can allow any project to be shared freely and the rights of software users protected.
Software released under the GPL license is considered ‘free software.’ However, it’s not because it is void of monetary obligations, but because it provides the liberation of access — or as the FSF likes to say, “free as in speech, not as in price.”
The four essential freedoms that underpin the GPL include:
- Freedom to run — you can use the program as you wish, for any purpose.
- Freedom to study — developers can study the original source code and how the program works.
- Freedom to modify — you can change the source code, so the program does what you want it to do.
- Freedom to distribute — you can redistribute the original program or distribute modified versions of it to others.
The GPL and free software model is popular among developers because it fosters creativity and provides no incentive to copy code as the software is built by a community of developers.
As long as all distributions of the software are also released under the GPL, both creators and users benefit from the open-source model as freedom is preserved downstream.
I mentioned before that GPL is a copyleft open source license. But what it is, exactly?
Copyleft is a creative twist on copyright law that exists to protect the above four freedoms.
While copyright law ensures that software cannot be redistributed or copied without proper permissions, copyleft sees to it that free software can be accessed, modified, and redistributed by anyone as long as versions of the program thereafter still remain free as well.
To sum up, copyright law typically protects the rights of its creators and restricts those of users, whereas copyleft protects and prioritizes the rights of users, and they will have their freedom with the software.
What is WordPress GPL?
Now that we’ve looked at the basic principles of copyleft licenses, let’s take a closer look at how WordPress operates under GPL.
WordPress was released under version 2 of the GPL, which, unlike the first version, adds a Liberty or Death clause. It states all users of the software must adhere to the four freedoms and can redistribute the modified versions only if all the freedoms are met.
There’s a debate about whether WordPress plugins and themes should be licensed under GPL or not.
A majority of the WordPress community, including its outspoken co-founder, Matt Mullenweg, argues that themes and plugins on WordPress are considered to be derivative works.
This is because those plugins and themes use the WordPress PHP code to be able to work properly, and can be seen as the extensions of WordPress. Thus, all of them need to be 100% GPL licensed.
This debate has never been tested in a court, so there’s no clear legal definition about this situation. However, you do get some perks if your themes and plugins are 100% GPL licensed.
The WordPress community is so passionate about keeping derivative works under the GPL that it has curated a directory of GPL-supported WordPress themes. That way, your works can easily reach a wider audience since they’re promoted by WordPress itself.
Understanding WordPress GPL for Commercial Use
There’s another common misconception that software products under GPL must be free of charge. This is actually false, because it is up to the developers whether or not to charge for their products.
So what’s the difference between GPL and non-GPL (copyrighted) products, then?
Well, as explained above, the idea that underpins GPL is the freedom to do whatever you want with the software. That includes the freedom to distribute it for free or for a certain amount of money. You can also charge a premium for value-added services like customer support and automatic updates.
That being said, even if you put a price on your GPL products, buyers will still have their freedom with it. They can study, modify, and distribute your software without your permission.
It’s a completely different case with proprietary software. Users have limitations on what they can do with the software, so they don’t have as much freedom with GPL products.
Now, the only case where you wouldn’t need to release WordPress-related works under GPL is if you have no plan to distribute it to anyone else.
To illustrate, if you were hired by someone else to design a website for them, you would be able to charge them for your services and not be required to license the website under the GPL as it is not a distributable work.
In this article, I’ve broken down that GPL is a copyleft license that governs open-source software products so users can have their freedom in using the programs.
Based on the four essential freedoms to run, study, modify, and distribute, GPL protects the rights of both users and developers by allowing software to be built on previous works, thus benefiting new users and original developers.
WordPress is currently running on version 2 of the GPL and are quite strict about their community following the provisions of the GPL.
I hope this article has been helpful to you in understanding the basics of the GPL.