[jupiter90000]

Exploratory data analysis. I may need to play around with loading data from a format I'm unfamiliar with, then do some basic summaries or information gathering about the data. This makes it straightforward to iterate on this type of stuff (instead of having to use command line REPL and press up arrows alot to re-run code sections without re-typing or pasting code). It's straightforward to share with someone familiar with Jupyter, and to a lesser extent with others who just need to look through the analysis results or code shown by the notebook. Though to be honest, when there isn't something about the analysis Python makes simpler, I find R with RStudio to have more flexibility for this kind of stuff, personally.