This visualization displays the Old Faithful dataset as a binned heatmap, using a 2x2 grid of repeated charts to explore relationships between four quantitative variables. Each cell shows the count of data points within binned ranges, colored on a green scale. The code uses Vega-Lite’s `repeat` operator and `bin` encodings, with an interactive slider controlling the `Maxbins` parameter. Data is loaded from a CSV via `d3.csv`, and rendering is handled by `vegaEmbed` with Vega-Lite specifications.