A yellow circle follows the mouse cursor across an SVG canvas, updating its position in real time with each pointer movement. The visualization uses React hooks (`useState` and `useCallback`) to manage mouse coordinates and trigger re-renders, while React’s synthetic `onMouseMove` event captures the cursor’s clientX and clientY values. Rendered as an SVG circle, the example demonstrates a simple interactive pattern leveraging D3’s presence only for the script tag, with React handling all state and rendering logic.