This example demonstrates a hierarchical tree visualization of car types, showing a root node labeled "Car" that branches into categories like Sedan, SUV, and Truck, each with two leaf nodes representing specific models. The visualization uses a color-coded encoding where the root is a red circle, the first-level categories are green squares, and the leaf nodes are blue triangles. Built with D3 version 5, the code constructs the tree layout using `d3.tree()` and `d3.hierarchy()`, and renders the SVG with cubic Bézier curves for links and distinct shapes per depth level. The data is a static JavaScript object with three levels of nesting.