A smiley face drawn with D3.js shows its eyebrows moving up and down in a looping animation. The code builds the face using SVG shapes: a yellow circle for the head, two circles for eyes, rectangles for eyebrows, and a path generated with the `d3.arc` function for the mouth. Eyebrow motion is created with chained `transition` and `duration` calls that alternate between two vertical positions. The example demonstrates fundamental DOM manipulation and data-driven styling using D3 v5’s selection, arc, and transition APIs.