copyleft (redirected from Copyleft licensing)

copyleft

A requirement in the GNU GPL software license and other "free" software licenses that anyone who redistributes the software does so under the same license and also includes the source code. The "free" means free of restrictions (see free software). The copyleft clauses were written to support the copyright laws, not to eliminate them.

Strong Vs. Weak Copyleft
A "strong copyleft" license, such as the GNU GPL license, applies to all derived works, whereas a "weak copyleft" license, such as the GNU Lesser GPL, applies only to the copylefted work, not other components in the package. See GNU General Public License and copyright.

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(legal)

copyleft - /kop'ee-left/ (A play on "copyright") The copyright notice and General Public License applying to the works of the Free Software Foundation, granting reuse and reproduction rights to everyone. Typically copyrights take away freedoms; copyleft preserves them. It is a legal instrument that requires those who pass on a program to include the rights to use, modify, and redistribute the code; the code and the freedoms become legally inseparable. The copyleft used by the GNU Project combines a regular copyright notice and the "GNU General Public License" (GPL). The GPL is a copying license which basically says that you have the aforementioned freedoms. The license is included in each GNU source code distribution and manual. See also General Public Virus.