A smiling face follows the mouse cursor across an SVG canvas, updating its position in real time as the pointer moves. The visualization uses React 16.9 with the `useState` and `useCallback` hooks to track mouse coordinates via the SVG `onMouseMove` event. A single circle is rendered at the current cursor position, with its `cx` and `cy` attributes bound to the state. The rendering is done entirely through React's declarative JSX, with no external data source or animation library.