This example shows a force-directed network of ten named nodes and nine weighted links, with node size fixed and link thickness scaled by the square root of each edge’s weight. It uses the D3 v4 `d3.layout.force` API (from the older v2 compatibility script) with gravity, charge, and distance parameters to position nodes, while SVG lines and circles render the graph. Node labels appear in blue text, and user interaction is supported via `force.drag`. The JSON data defines groups and link weights, which drive the visual encoding.