An interactive, animated tree diagram displays a static, hierarchical dataset of nodes with names and sizes, such as “node 10” and “root.” Users click nodes to expand or collapse their children, with smooth transitions repositioning nodes and links over 750 milliseconds. Built with D3.js, the example uses `d3.layout.tree`, `d3.svg.diagonal`, and SVG transitions to render the structure, styling circles and paths via CSS. Data is hardcoded in JavaScript, and rendering uses SVG with animation.