Knowra Copyleft Copyleft Copyleft is a licensing approach that permits copying, modification, and distribution while requiring derivative works to preserve those freedoms under the same or compatible terms.
Copyright : Copyright is a set of legal rights that governs copying, distribution, adaptation, and public performance of creative works. Copyleft uses copyright to make its permissions and redistribution conditions legally enforceable.
Free software : Free software gives users the freedom to run, study, modify, and share the software. Copyleft is one way to preserve these freedoms in modified and redistributed versions.
GNU General Public License : The GNU General Public License is a family of software licenses requiring covered redistributed derivatives to remain under the same license. The GPL is the best-known strong copyleft license for software.
Richard Stallman : Richard Stallman is an American programmer and free-software activist who founded the GNU Project and the Free Software Foundation. Stallman developed the GNU project and licensing strategy that made copyleft a practical movement.
Derivative work : A derivative work adapts or transforms an existing work, incorporating protected expression from it. Whether changes count as derivative works determines when copyleft terms apply.
Public domain : The public domain consists of works not restricted by copyright, so anyone may generally use them without permission. Unlike public-domain dedication, copyleft retains copyright to enforce conditions on redistribution.
GNU Lesser General Public License : The GNU Lesser General Public License permits linking to covered libraries under conditions less restrictive than the GPL. The LGPL applies copyleft to library code while allowing broader use by other software.
GNU Project : The GNU Project is a long-running effort to develop a Unix-like operating system composed entirely of free software. The project's need to protect users' freedoms drove the creation of the GPL.
License compatibility : License compatibility is the ability to combine or redistribute works governed by different licenses without violating their terms. Compatibility determines whether copyleft material can be combined with differently licensed works.
Permissive license : A permissive license allows reuse with few conditions, typically without requiring derivative works to retain the same license. Permissive terms allow derivatives to become proprietary, unlike copyleft's reciprocity requirement.
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