This comparison only covers software licenses which have a linked Wikipedia article for details and which are approved by at least one of the following expert groups: the Free Software Foundation, the Open Source Initiative, the Debian Project and the Fedora Project.
There is no one universally agreed-upon definition of FOSS software and various groups maintain approved lists of licenses.
The Open Source Initiative (OSI) is one such organization keeping a list of open-source licenses.
[6][7] The OSI's open-source criteria focuses on the availability of the source code and the advantages of an unrestricted and community driven development model.
"Copyleft" means the software requires that its source code be made publicly available and that all provisions in the license be preserved in derivative works.