A smiley face rendered as a yellow SVG circle with black stroke, two empty eye circles, and an interactive white dot that follows the cursor via a mousemove event listener. The face uses React’s JSX syntax to define SVG elements, with coordinates computed from the browser window’s width and height (window.innerWidth, window.innerHeight) for centering. The code imports React and ReactDOM, and renders the app to a root div, while a commented-out static SVG shows an alternative fixed-size version.