Chini Gianalberto 17.04.2008 ` Python Software Foundation License was created in early 1990s and the main author is Guido van Rossum. The last version is 2.4.2 released 2005 by PSF (Python Software Foundation). ` The major purpose of PSFL is to protect the Python project software. ` PSFL is a permissive free software license that allows “a nonexclusive, royalty-free, world-wide license to reproduce, analyze, test, perform and/or display publicly, prepare derivative works, distribute, and otherwise use Python 2.4 alone or in any derivative version” (PSFL) ` This means... ` Python is free and you can distribute for free or sell every product written in python. ` You can insert the interpreter in all applications you want without to pay. ` You can modify and redistribute software derived from Python. ` PSFL copyright notice must be retained in every distribution of python or in every derivative version of python. This clause is in guarantee of python creator’s copyright. ` The main difference between GPLv3 and PSFL is that the first one is copyleft in contrast with PSFL. ` Since PSFL is a copyleft license, it isn’t required that the source code must be necesserely released. ` Only binary code of python or derivative works can be distribuited. ` Only binary code of python modules can be distribuited. ` But… PSFL is fully compatible with GPLv3 ` The 1.6.1PSFL version is not GPL-compatible because “the primary incompatibility is that this Python license is governed by the laws of the State of Virginia, in the USA, and the GPL does not permit this.” (Free Software Foundation). ` The versions following 2.0.1 are all GPL-compatible, this means that is possible to combine a PSFL software with another GPL software..