July 21, 2009
One of the more common misconceptions about the GPL is that it is “viral” in nature and can “infect” any software that touches it.
While it is true that the GPL does have a viral component, it is only to ensure that derivative works based upon GPLed code are also released to the GPL. It is possible, and even common, for GPL applications and proprietary ones to co-exist side by side. For example, there are many proprietary programs, including Skype and MyDropBox, that run on Linux, which is GPLed.
However, when one delves into plugins and and themes, something of a gray area begins to emerge. Though a WordPress theme, for example, might not be based upon a GPL theme, it relies upon a GPL application to function. As such, it has been widely held that they are GPL-licensed, even if they haven’t been explicitly licensed as such. read more