Definition - What does GNU General Public License (GPL) mean?

The GNU General Public License (GPL) is a free, copyleft license used primarily for software. The GNU GPL allows users to change and share all versions of a program. GPL is provided through the Free Software Foundation, a nonprofit corporation that works to provide free software for the GNU Project.

Techopedia explains GNU General Public License (GPL)

In 1989, Richard Stallman produced the first GPL through the GNU Program. The GNU Program was launched in 1984 for the express purpose of developing operating systems that are similar to Unix, except that they are open source. Under the GPL provisions, owners may sell copies of programs under GPL, or distribute them for free. To do so, licensees must adhere to the designated terms and conditions of the GPLs. Under a GPL, owners are permitted to modify digital materials as well. The GPL is widely used and the most popular free license of its kind.

The first term of the GPL states that programmers may freely copy and distribute verbatim copies of a software program's source code, under the condition that each copy displays a copyright notice, disclaimer of warranty, intact GPL notices, and a copy of the GPL. The second term of the GPL, which deals with modification and redistribution of software, requires the same conditions as the first, along with notification of any changes made to the software.

The GPL itself is under the copyright ownership of the Free Software Foundation (FSF), a tax-exempt charity organization founded by Stallman's GNU project in order to generate funding for free software development.