This example presents a collapsible tree visualization where each node is a labeled box, colored by type, and connected by curved links with arrows. The tree expands and collapses nodes with animated transitions. It uses the D3.js v3 layout `d3.layout.tree` and applies a breadth-first traversal to size the SVG canvas dynamically, color nodes, and resolve collisions. Pan and zoom are enabled via `d3.behavior.zoom`, and custom tooltips appear on hover. The data comes from a JSON file with nested node objects.