What is Copyleft?
Copyleft is a licensing strategy that uses copyright law to ensure software remains free and open. By requiring derivative works to be distributed under the same license, it creates a self-replicating ecosystem of openness.
Creative Commons ShareAlike
CC-BY-SA licenses allow modification and distribution as long as derivatives carry the same license.
GNU Licenses
GPL, LGPL, and other GNU licenses form a robust framework for free software development and collaboration.
Legal Foundations
GPLv3
The latest version of the GNU General Public License with enhanced protections against Tivoization.
LGPL
GNU Lesser General Public License allows library linking without forcing entire projects to be open-source.
Mozilla
Balances open-source development with permissive clauses for enterprise adoption.
License in Action
// Sample MIT License Clause Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
Note:
This is simplified. Always consult the official license text for complete terms.