A React application demonstrates mouse tracking by rendering a single SVG circle that follows the cursor. The component uses React's `useState` hook to store the mouse position and a `useCallback` hook to handle the `onMouseMove` event, updating the circle's `cx` and `cy` attributes. The visualization renders through ReactDOM into an SVG element with a fixed 960 by 500 viewport, showing how React state drives interactive SVG updates without any external data loading or D3 dependencies.