GNU General Public License

Overview

The GNU General Public License is a free software license, written by Richard Stallman for the GNU project. The latest version of the license, version 3, was released in 2007. The GNU Lesser General Public License (LGPL) is a modified version of the GPL, intended for software libraries.

GNU General Public License is the most popular license for free software.

Freedom

The GNU GPL grants the recipients of a computer software program the following rights/freedom:

The freedom to run the software program, for any purpose.
The freedom to study how the software program works, and modify the program.
The freedom to redistribute the modified software copies.
The freedom to improve the software program, and release the improvements to the public.

Access to the source code is a precondition for studying the software program and improving it.

GPL is a copyleft license. GPL seeks to ensure that the above freedoms are preserved in copies and in derivative works. It requires derivative works of GPL-licensed software programs to also be licensed under the GPL.