A circle follows the mouse cursor across an SVG canvas, updating its position in real time. The visualization uses React with the `useState` hook to track mouse coordinates and rerender the circle’s `cx` and `cy` attributes. The app is built with React and ReactDOM, rendered into a full-screen SVG, with styling that hides page margins and scrollbars. The mouse movement is captured via an `onMouseMove` event handler on the SVG element.