Python 2.x is an older version compared to Python 3.x. Python 3.x was first developed in 2008 while the last Python 2.x update came out in 2010. Though it is perfectly fine to use table application with the 2.x, it is worthwhile to mention that 2.x has not been developed any further from 2.7. 

Almost every machine learning package in use has support for both the 2.x and the 3.x versions. However, for the purposes of staying up-to-date, we will be using version 3.x in the uses cases we discuss in this book.