What is the GPL? A Deep Dive for WordPress Users and Developers
If you‘re new to WordPress or open source software in general, you may have heard the term "GPL" thrown around but felt unsure about what it really means. In this section, we‘ll break down the key concepts behind the GNU General Public License (GPL) and why it matters so much for WordPress and beyond.
The Basics of Free and Open Source Software
At its core, the GPL is a free and open source software license. But what does that actually mean?
When we say software is "free," we‘re not necessarily talking about price. Instead, "free software" refers to the freedoms users have in relation to the software. As defined by Richard Stallman and the Free Software Foundation (FSF), free software grants users four key freedoms:
- The freedom to run the software for any purpose
- The freedom to study the source code and modify it however you wish
- The freedom to share and redistribute the software to others
- The freedom to distribute your own modified versions of the software
These freedoms are at the heart of the free software movement and the GPL. The goal is to empower users and foster collaboration, not restrict how software can be used and shared.
"Open source" software is closely related to free software but tends to focus more on the practical benefits of making source code available. While free software emphasizes user freedoms as a moral imperative, open source proponents highlight how allowing anyone to view, modify, and contribute to software code leads to more innovative, secure, and efficient software development.
Copyleft: The GPL‘s Secret Weapon
One of the key innovations of the GPL is its use of "copyleft" provisions to keep software free and open in perpetuity. But what is copyleft, and how does it work?
In simple terms, copyleft is a clever hack of copyright law to ensure user freedoms are always preserved, even as software is modified and shared. The GPL requires that any derivative works – meaning software built using GPL-licensed code – must also be released under the GPL. This means the GPL and its freedoms are "viral" and persist as the software evolves and spreads.
To illustrate, let‘s say a developer takes a piece of GPL-licensed code, modifies it, and includes it in her own software program. Under the terms of the GPL, that entire program must now be licensed under the GPL as well. The developer cannot take the GPL-licensed code and use it in a proprietary, closed-source application.
This might sound restrictive, but the goal is actually to maximize user freedom. Without copyleft, a company could take free and open source code, make a few changes to it, and then release the resulting program under a proprietary license that limits user freedoms. Copyleft prevents this by ensuring the code and its freedoms are inseparable.
Richard Stallman has described copyleft as a way of "using copyright law, but flipping it over to serve the opposite of its usual purpose: instead of a means for restricting a program, it becomes a means for keeping the program free."
The GPL and WordPress: A Perfect Match
So what does all of this have to do with WordPress? As it turns out, everything.
WordPress is licensed under the GPL, which has been crucial to its success and growth as a content management system (CMS). By using a free and open source license, WordPress has been able to attract a massive global community of developers, users, and advocates who contribute to the software and help drive its evolution.
Some key stats that demonstrate the impact of the GPL and open source on WordPress:
- WordPress now powers over 40% of all websites on the internet (W3Techs)
- The WordPress plugin directory features over 59,000 free plugins that extend the software‘s functionality (WordPress.org)
- The WordPress theme directory offers over 9,000 free themes for designing and customizing WordPress sites (WordPress.org)
- Over 1,100 developers have contributed to WordPress core since version 3.0 (WordPress.org)
The GPL has made all of this possible by ensuring that WordPress and its ecosystem of extensions remain free and open for anyone to use, modify, and build upon. Without the GPL, WordPress may never have grown into the web powerhouse it is today.
Of course, the GPL does present some challenges and tradeoffs, especially when it comes to commercial WordPress products. We‘ll explore those in more detail later on. But the overwhelming consensus within the WordPress community is that the GPL and its ethos of freedom and collaboration have been vital to the project‘s success.
As WordPress co-founder Matt Mullenweg has put it: "WordPress wouldn‘t be where it is today without the GPL. The license has been a key part of creating a vibrant, collaborative community around the software and ensuring that it remains open and accessible to everyone."
Other Common Software Licenses: How They Compare to the GPL
The GPL is just one of many software licenses out there, each with its own unique terms and conditions. To help put the GPL in context, here‘s a quick comparison of some other common licenses:
| License | Key Terms | Compatibility with GPL |
|---|---|---|
| MIT | Permissive license that allows for proprietary derivative works | Compatible |
| BSD | Permissive license similar to MIT | Compatible |
| Apache 2.0 | Permissive license that grants patent rights | Compatible |
| LGPL (Lesser GPL) | Weak copyleft license that allows linking with proprietary code | Compatible |
| MPL (Mozilla Public License) | File-level copyleft license | Partially compatible |
| Proprietary (e.g. Microsoft, Oracle) | Restrictive licenses that limit usage, modification, and distribution | Incompatible |
As you can see, the main difference between permissive licenses like MIT and the GPL is that the GPL requires derivative works to be licensed under the GPL as well. Proprietary licenses, on the other hand, place strict limits on how software can be used and shared and are generally incompatible with the GPL.
The Future is Open
It‘s clear that the GPL and open source software have had a profound impact on WordPress and the broader tech landscape. But what does the future hold?
One thing is certain: the genie is out of the bottle when it comes to free and open source software. What started as a niche movement has now become mainstream, with major companies like Google, Microsoft, and IBM embracing open source and contributing to projects like Linux, Kubernetes, and React.
WordPress, too, shows no signs of slowing down. With a dominant market share and a thriving ecosystem of plugins and themes, WordPress is well-positioned to continue its growth and evolution in the coming years. And the GPL will undoubtedly remain a key part of that journey.
Of course, there will always be challenges and debates around the GPL and how it should be applied and enforced. But one thing is clear: the WordPress community remains committed to the ideals of free and open source software and to ensuring that WordPress remains a platform that empowers users and fosters collaboration.
As a WordPress user or developer, understanding the GPL and its role in the project is essential. By embracing the freedoms and opportunities made possible by the GPL, you can help contribute to the ongoing success and growth of WordPress. So go ahead and dive in – the water‘s warm, and the future is open.
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