A black circle on a white SVG canvas follows the mouse cursor in real time. The React component uses the `useState` hook to track the mouse position, updating it via the `onMouseMove` event handler on the SVG element. The circle’s `cx` and `cy` attributes are bound to the current `clientX` and `clientY` coordinates, and both React and ReactDOM are loaded from CDN. The visualization demonstrates simple interactive state management and SVG rendering within a React application.