A smiling face is drawn in SVG using React, with a yellow circular head, black stroke outline, and two black eyes positioned symmetrically. The mouth is an arc created with the `d3.arc` generator, using a 130-pixel inner radius and a half-circle angular span. The entire face is centered on the screen using a translated `<g>` group. The code relies on `d3.arc` from d3.v6, React 17, ReactDOM, and a hardcoded width of 960 and height of 500 for the viewport.