For years people have suggested that open-source adoption would go even faster if only open-source licenses like the GNU General Public License (GPL) were easier to understand. My personal belief is that "It's so hard to understand!" tends to be an euphemism for "I really want to pilfer this open-source software but its terms don't let me!" After all, the terms of the GPL have been explained repeatedly, including by the Free Software Foundation itself, which authored the GPL.
Regardless, the Software Freedom Law Center is now making it easy to understand the GPL and related licenses with a guide (available online) that walks through effective compliance:
Unlike highly permissive FOSS licenses (such as the ISC license), which typically only require preservation of copyright notices, the GPL places a number of important requirements upon licensees. These requirements are carefully designed to uphold certain values and standards of the software freedom community. While the GPL's requirements may appear initially counter-intuitive to those more familiar with proprietary software licenses, by comparison its terms are in fact clear and favorable to licensees. The terms of the GPL actually simplify compliance when violations occur.
GPL violations are often caused or compounded by a failure to adopt sound practices for the incorporation of GPL'd components into a company's internal development environment. In this section, we introduce some best practices for software tool selection, integration and distribution, inspired by and congruent with FOSS methodologies.
What follows, then, is a highly practical walk-through of how to use GPL software, when to release derivative works, etc. Any company that uses GPL software - which includes roughly 99.999 percent of IT departments due to the rise of Linux - should get a copy of this compliance guide and study it. Ignorance is no longer an excuse for a lack of compliance with open-source license compliance.