Information Technology Reference
In-Depth Information
12
Figure 12.4
It's not exactly one-stop
shopping, but the
Commercial Themes
Directory at WordPress
.org lets you visit pre-
mium theme developers
from one handy place.
The GNU General Public License
We have occasionally mentioned the GNU General Public License (GPL). This is one of the legal
engines that makes open source software go. There are many open source licenses (see
http://opensource.org/licenses for a complete list), but the GNU GPL is the most common.
In many ways, the GPL codifies the principle of “share and share alike” with software. Essentially
when one programmer puts code under the GPL, it tells other programmers that they can freely use
the code in other software projects, but when they do, they have to grant the same rights to others.
The GPL also allows anyone to look at the code and customize it to meet a need they have. That
need, or the particular solution, may not be for every other user of the software, but it has to be
available to all other users. This is one reason we have plug-ins in WordPress.
Some history: Richard Stallman of the Free Software Foundation wrote the original GPL in 1989 to
cover applications included in the GNU (GNU's Not UNIX) project to develop a non-proprietary ver-
sion of the UNIX operating system. Version 2 of the GPL was released in 1991, and is the most
widespread version of the license. WordPress, the kernel of the GNU/Linux operating system, the
Mozilla Firefox browser, and many other prominent projects are covered by this version. The third
version of the GPL was released in 2007 to some controversy around provisions concerning digital
rights management and software patents. Bruce Byfield offers a good description of this philo-
sophical debate at http://bit.ly/v9uHN. Some projects continue to be released under GPLv2, and
others under GPLv3.
Continued…