This example shows a small network of seven named nodes connected by six links, with node groups and link weights visible through circle styling and stroke width. It uses a force-directed layout via `d3.layout.force` to position nodes, with SVG rendering for lines, circles, and text labels. The code loads node and link data from a JSON file and supports dragging nodes through `force.drag`. Styling is applied with CSS, and the visualization updates on each tick of the force simulation.