This visualization combines a scatter plot matrix with histograms along the diagonal to explore the classic Iris dataset. Using D3.js v5 with SVG rendering, it displays pairwise relationships between four flower measurements, colored by species. When users select data points, the histograms dynamically update to show the distribution of selected measurements. The code uses D3's `scalePoint`, `scaleLinear`, and `histogram` APIs to arrange the plots and compute bin counts, with the Iris dataset loaded from a local CSV file.