Python Software Foundation License
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The Python Software Foundation License is a free software license which is compatible with the GNU General Public License (GPL). It's primary use is for distribution of the Python project software.
Early versions of this license were not compatible with the GPL. The reason given by Free Software Foundation 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."
The year that Guido van Rossum, Python's creator, changed the license to fix this incompatibility, he was awarded the Free Software Foundation Award for the Advancement of Free Software - possibly due to his agreement to change the Python license.