A circle follows the mouse cursor across an SVG canvas, updating its position in real time as the pointer moves. The React application tracks the mouse’s client coordinates and renders a single circle centered on that point. It uses the `useState` hook to store the cursor position and the `onMouseMove` event on the SVG element to trigger updates. The visualization is built with React and ReactDOM, rendering SVG directly in the browser with a fixed canvas size of 960 by 500 pixels.