This example shows a hierarchical tree of programming languages, grouping frontend, backend, and data science categories with their child technologies. Developed with D3 v7, it uses `d3.hierarchy` and `d3.tree` to compute node positions, then renders curved `d3.linkVertical` paths for connections and SVG circles for nodes. Node colors vary by depth—orange for the root, teal for categories, and blue for leaves—with text labels above each circle. The static dataset is hard-coded in the script, and the output is a 900x500 SVG visualization.