This example shows a force-directed network graph with 20 nodes arranged in a circle and connected sequentially by links. Using D3 v7, it employs `d3.forceSimulation` with link, charge, and center forces to animate the layout. Nodes are rendered as SVG circles with labels, and drag behavior is implemented via `d3.drag` to reposition nodes interactively. The data consists of synthetic nodes and links generated with `d3.range`, and the visualization updates positions on each simulation tick.