The document discusses the GNU GPL (General Public License) and free/open source software licensing. It provides definitions of a software license and different types of licenses. The GNU GPL was created by Richard Stallman for the GNU project to provide four essential software freedoms: the freedom to run software, redistribute it, modify it, and redistribute modified versions. The GPL ensures that any software or works using it also grant users these four freedoms. Popular free/open source software like Linux, LibreOffice, and DSpace use the GPL to remain freely accessible and modifiable by users.