A D3.js example demonstrates fundamental DOM manipulation by rendering a yellow smiley face with animated eyebrows. The SVG circle forms the face, while `d3.arc()` creates the mouth path. The code uses D3 selections and transitions to move rectangular eyebrows vertically over two seconds, then back. It imports `select` and `arc` from d3.v5, builds the graphic in an SVG container, and animates the eyebrow group's transform attribute.