A React application renders a full-screen SVG that displays a single black-outlined circle following the mouse cursor. The circle’s position updates dynamically via React’s `useState` and `useCallback` hooks, which capture `event.clientX` and `event.clientY` from the SVG’s `onMouseMove` handler. Built with React 16.9 and rendered through `ReactDOM.render`, the visualization uses SVG elements to draw the circle and relies on the browser window dimensions for its initial sizing.