A smiley face built with D3.js demonstrates fundamental DOM manipulation and animation. The code uses `d3.select` to append SVG circle and rectangle elements for the face, eyes, and eyebrows, while a D3 arc path creates the mouth. Eyebrow movement is shown through chained `transition` calls that animate the group's transform attribute over two-second durations. The yellow face with black outlines highlights basic SVG rendering and D3's data-driven approach to styling and positioning.