What does GPL stand for?

General Public License

The agreement under which software, such as the GNU (GNU’s Not UNIX) utilities, is distributed by the Free Software foundatioanyone who has a copy of such a program may redistribute it to another party and may charge for distribution and support ser-vices, but may not restrict the other party from doing the same. A user may modify the program, but if the modified version is distributed, it must be clearly identified as such and is also covered under the General Public License.