A smiling face built with SVG demonstrates basic D3.js DOM manipulation and animation. Drawn with a yellow circle, two eyes, rectangular eyebrows, and an arc-based mouth, the face animates by moving the eyebrows upward and back down using chained `transition().duration()` calls. The example uses D3 v5’s `select`, `arc`, and `attr` methods to construct and style elements, with the eyebrow displacement triggered automatically on load.