there are two major versions of python that are widely used at the momentpython (more precisely and python (with the latest release being at the time of writingthis sometimes leads to some confusion python is no longer actively developedbut because python contains major changespython code usually does not run on python if you are new to pythonor are starting new project from scratchwe highly recommend using the latest version of python without changes if you have large codebase that you rely on that is written for python you are excused from upgrading for now howeveryou should try to migrate to python as soon as possible when writing any new codeit is for the most part quite easy to write code that runs under python and python if you don' have to interface with legacy softwareyou should definitely use python all the code in this book is written in way that works for both versions howeverthe exact output might differ slightly under python versions used in this book we are using the following versions of the previously mentioned libraries in this bookin[ ]import sys print("python version{}format(sys version)import pandas as pd print("pandas version{}format(pd __version__)import matplotlib print("matplotlib version{}format(matplotlib __version__)import numpy as np print("numpy version{}format(np __version__)import scipy as sp print("scipy version{}format(sp __version__)import ipython print("ipython version{}format(ipython __version__)import sklearn print("scikit-learn version{}format(sklearn __version__) the six package can be very handy for that introduction