This example shows a family tree rendered as an interactive hierarchical diagram, with nodes representing people and links showing parent-child relationships. Users can click on nodes to expand or collapse their children, while smooth transitions animate the tree’s layout changes. Built with D3.js v3, it uses `d3.layout.tree` to compute positions and `d3.svg.diagonal` for curved links, with SVG circles and text for nodes. The data is hardcoded as nested JavaScript objects, and the visualization responds to user interaction via click handlers.