A smiley face rendered with D3.js demonstrates basic DOM manipulation and animation. The code uses D3 selections to append SVG circles for the face and eyes, rectangles for eyebrows, and an arc-generated path for the mouth. A two-stage `transition` moves the eyebrow group vertically over four seconds, creating an animated expression. The face is centered via SVG transforms, with all shapes drawn using D3's `select`, `append`, `attr`, and `transition` APIs.