GNU General Public License

The GNU General Public License (GPL) is a family of software licenses that grants users freedoms to run, study, modify, and redistribute software while requiring covered derivative works to preserve those freedoms.

Copyleft: A licensing principle that permits reuse while requiring certain redistributed adaptations to retain comparable freedoms. The GPL is the best-known implementation of copyleft for software.
GNU Project: A project launched by Richard Stallman in 1983 to develop a Unix-like operating system composed of free software. The GPL was created to support the GNU Project's software-sharing aims.
GNU Lesser General Public License: A copyleft license that permits linking with certain non-GPL programs under specified conditions. It offers a narrower reciprocity model, especially for software libraries.
Linux kernel: The kernel of the Linux operating system, licensed under version 2 of the GNU GPL. It is a prominent GPL-licensed project whose license excludes certain forms of additional restrictions.
Free software: Software whose license grants users the freedoms to run, study, modify, and share it. The GPL translates these four freedoms into terms for covered software.
Source code: Human-readable instructions that programmers write and that compilers or interpreters can translate or execute. The GPL requires corresponding source in specified forms of distribution.
Richard Stallman: An American programmer and free-software activist who founded the GNU Project and the Free Software Foundation. He wrote the first GPL and articulated its underlying freedoms.
GNU Affero General Public License: A copyleft software license that can require network users to receive source for modified versions used as services. It addresses network interaction where ordinary GPL distribution triggers may not apply.
GNU Compiler Collection: A collection of compilers for languages including C, C++, and Fortran, distributed as free software under the GPL. Its distribution illustrates GPL licensing across widely used development tools.
GNU Manifesto: A 1985 essay by Richard Stallman explaining the goals of the GNU Project and asking for support. Its case for software sharing provides context for the GPL's purpose.

Linked from 13 pages