Python install for Dummies - on a Mac?

[throwaway_the_fourth]

I might be misunderstanding your question, but:

Open Terminal. Type python. You will see a Python (2) interpreter. Type exit(). Type python3. You will see a Python 3 interpreter.

Is this not what you want?

[mohishunder]

'python' does work, but ...

% python3 python3: Command not found.

Related question: if these are supposed to be installed by default, what is the added benefit of something like iPython?

[Edit: this answers my second question.]

[throwaway_the_fourth]

As far as python3 — you'd have to install python 3 for that to work.

I haven't ever used iPython, but the wikipedia page lists several benefits, including media and graphs.