The most widely used Open Source and Free Software license, the GNU General Public License, is a copyleft license. Copyleft is a legal hack on the typical manner that copyright is used. Typically, proprietary software companies use copyright to restrict the user from engaging in the core activities that copyright governs for software: copying, modifying, and redistributing the software. By contrast, copyleft licenses encourage users to share and improve their software — both commercially and non-commercially. Most importantly, a copyleft license assures users’ rights to receive necessary technical details, including but not limited to the software’s source code, so that they can fully and easily exercise their rights.
Since its inception, copyleft has also been applied to all sorts of works other than software, including documentation, movies, photos, novels, and websites.
This talk provides a full introduction to the concepts behind copyleft. No prerequisite knowledge is assumed; attendees can show up totally new to Open Source and Free Software licensing, and leave with a clear idea of how copyleft works, and have a basic introduction to current issues and challenges that we face in the world of copylefted software.