A single yellow circle follows the mouse cursor across an SVG canvas, using React state to track pointer position. The app renders a `<circle>` element whose `cx` and `cy` attributes update on every `mousemove` event via the `onMouseMove` handler, with coordinates stored in the `mousePosition` state. It uses React hooks `useState` and `useCallback` within a React functional component, rendering directly through `ReactDOM.render`. No external data or animation libraries are involved; interaction is purely event-driven.