What is the difference between Python and IPython?

Question

What exactly is the difference between Python and IPython?

If I write code in Python, will it run in IPython as is or does it need to be modified?

I know IPy

Answer 1

Even after viewing this thread, I had thought that ipython was a synonym for the python shell, in other words that typing python at the command line put one into ipython mode.

It is in fact, as referenced above, a very cool interactive shell (command line program) that can be installed from iPython.org or simply by running

pip install ipython

or the more extensive:

pip install ipython[notebook]

from the command line.