A smiley face drawn with SVG shapes animates its eyebrows in a looping motion. The example demonstrates fundamental D3.js DOM manipulation by using `select` to target SVG elements and `append` to build circles, rectangles, and a path arc for the mouth. A chained `transition().duration()` sequence moves the eyebrow group up and down over two-second intervals. The face is centered on a 960-by-500 viewport, with all coordinates offset from the middle via a translation transform.