A D3.js network graph visualizes a hierarchical dataset of experts and strategic technology topics, using color-coded nodes and connecting links. Rendered as SVG, the graph supports zooming via `d3.zoom` and dragging nodes through `d3.drag`, with positions computed by a force simulation. A "Switch" button dispatches a custom event, though the graph itself does not visibly change in response, and the code includes a template-prefilled smiley-face title that is not implemented in the visualization.