A smiling face composed of SVG shapes demonstrates D3.js fundamentals by animating its eyebrows upward and downward in a looping sequence. The code builds the face using `d3.select`, `d3.arc`, and chained `transition` calls on SVG elements like circles, rectangles, and a path for the mouth. Eyebrow motion is achieved through attribute transformations applied over two-second durations, while the static face relies on hardcoded numeric values for positioning and sizing. The rendering is entirely SVG-based, with no external data source.