Pip is the python equivalent of "linux redhat's yum"
It comes included with python 3.4.
it is something that you run from the powershell command line rather than within python terminal itself, e.g.
PS C:\Users\Mir\Desktop=> pip install -U selenium
Running setup.py (path:C:\Users\Mir\AppData\Local\Temp\pip_build_Mir\selenium\setup.py)
egg_info for package selenium
Installing collected packages: selenium
Running setup.py install for selenium
Successfully installed selenium