Python is a programming language that lets you work more quickly and integrate your systems more effectively. You can learn to use Python and see almost immediate gains in productivity and lower maintenance costs.
Python runs on Windows, Linux/Unix, Mac OS X, and has been ported to the Java and .NET virtual machines.
Python is free to use, even for commercial products, because of its OSI-approved open source license.
Esri has adopted Python as the primary scripting language for ArcGIS.
ArcGIS Desktop includes Python 2.7x32 (Desktop), 2.7x64 (Desktop background geo processing) and Python 3.5x64 (ArcGIS Pro)
USGS has a Python mailing list: GS_Help_Python@usgs.gov - list archive
To join the GS Help Python list, send a request to Shane Wright (firstname.lastname@example.org)