The General Public License is a free, copyleft license for software and other kind of stuff. The GPL is intended to guarantee you the freedom to share and change all versions of a program. But please make no mistake. When we speak of free software, we are referring to freedom, not price. The General Public Licenses are designed to make sure that you have the freedom to distribute copies of free software, that you receive source code or can get it if you want it, that you can change the software or use pieces of it in new free programs, and that you know you can do everything mentioned above.