OSI Approved Licenses Open source licenses are licenses that comply with the Open Source Definition – in brief, they allow software to be freely used, modified, and shared. To be…| Open Source Initiative
What is Copyleft?| www.gnu.org
Since 1983, developing the free Unix style operating system GNU, so that computer users can have the freedom to share and improve the software they use.| www.gnu.org
GNU GENERAL PUBLIC LICENSE| www.gnu.org