This example shows an interactive family tree for the British royal family, with nodes representing individuals like King Charles, William, and Harry, and colored rectangles indicating different generations or types. The visualization uses D3.js v3 with a tree layout and SVG rendering, featuring expandable/collapsible nodes, tooltips, and animated transitions. It loads hierarchical JSON data and renders custom-styled node boxes with colored fills, drop shadows, and arrow-marked links. The code also implements zoom and drag behavior with mouse wheel support, alongside collision detection and a breadth-first traversal to manage node positions and depth-based spacing.