= General Public Licence.
"The 'free' in free software is safeguarded by a specific software licence, the General Public Licence (GPL) which is maintained by the Free Software Foundation. The legal and normative basis of FLOSS are enshrined as four freedoms in the GPL. These are: freedom to use a work, freedom to change it, freedom to distribute exact copies of it and freedom to distribute adapted copies. These freedoms are made practicable through the obligation to provide the necessary resources - for software, this is the human-readable source code."