Python versions in Ubuntu

Ubuntu comes with both python versions 2.x and 3.x.
The default python version in ubuntu is 2.x

The python versions installed in ubuntu can be found using the below commands:
For both cases, to get out from Python shell, write:

 exit()

For installing python modules in python 2.x in ubuntu, use  :

pip

For installing python modules in python 3.x in ubuntu, use:

 pip3