What is the GNU General Public License (GPL)?
The GNU General Public License (GPL) is a free copyleft license mainly used for software. The GNU GPL allows users to change and share all versions of a program. GPL is made available by the Free Software Foundation, a non-profit organization that provides free software for the GNU Project.
In 1989 Richard Stallman produced the first GPL through the GNU program. The GNU program was started in 1984 with the express aim of developing operating systems that are similar to Unix, except that they are open source.
Under the terms of the GPL, owners can sell copies of programs under the GPL or distribute them free of charge. To do this, licensees must comply with the terms set out in the GPL. Under a GPL, owners are allowed to modify digital materials as well. The GPL is widespread and the most popular free license of its kind.