GNU GPL is the most well-known and extensive free software license. The GPL permits the usage, change and distribution of software and forbids the exclusion of usage software, such as reprivatization of software that was derived from them.

Abbreviation for the GNU General Public License. See http://www.gnu.org.

The GNU GPL (online at http://www.fsf.org/copyleft/gpl/html) is a license for software which guarantees continuing rights to these freedoms: The freedom to run the program, for any purpose (freedom 0).The freedom to study how the program works, and adapt it to your needs (freedom 1). Access to the source code is a precondition for this. The freedom to redistribute copies so you can help your neighbor (freedom 2). Freedom to improve the program, and release your improvements to the public, so that the whole community benefits (freedom 3). Access to the source code is a precondition for this. This definition of freedom is taken from the Free Software Foundation website: http://www.fsf.org