A hierarchical tree diagram displays a professor as the root node with three children, each branching to two or three leaf nodes. Rendered using D3.js v3 and SVG, the visualization features green circles connected by violet diagonal links and includes animated transitions when nodes are clicked. The tree layout uses `d3.layout.tree` and `d3.svg.diagonal` projections, with click handling that collapses or expands child nodes while updating positions smoothly.