An always-reactive notebook is essentially a "literate spreadsheet", where you have data cells in between multimedia descriptions. In this model, all computed d

An always-reactive notebook is essentially a "literate spreadsheet", where you have data cells in between multimedia descriptions. In this model, all computed data is always up to date with whatever changes you make to the input parameters, including things like graphics connected to interactive sliders and text boxes. You can prototype the logic of an application very fast with real data and interactions.