This example shows an interactive family tree using a hierarchical node-link diagram, with each person represented as a colored circle and labeled with their name. The tree is built from a static JavaScript array and rendered with SVG, where nodes collapse and expand on click, and transitions animate position changes over 750 milliseconds. Using D3.js version 3’s `d3.layout.tree` and `d3.svg.diagonal`, the code computes the layout and draws curved links, while node fill and stroke colors encode the person’s type and level fields.