A smiling face is rendered as a yellow circle with black outline, two eyes, and an arc-shaped mouth, all centered within an SVG. The visualization is built with React components, where each facial feature is a separate file and uses ES6 modules and React Fragments. D3’s `arc` generator creates the mouth path, while styling and positioning come from inline SVG attributes. The code is a fork from a tutorial, with React handling the component structure and D3 providing the arc geometry.