This example visualizes a research collaboration network using D3.js v7’s force-directed layout. Nodes represent researchers, institutions, projects, and organizations, colored by group and connected by directed links with arrowheads. Hovering over a node reveals a tooltip with details like role, field, and country. The graph uses `d3.forceSimulation` with `d3.forceLink`, and positions are fixed via `fx`/`fy` properties while SVG circles, labels, and markers are rendered dynamically.