A smiling face built from SVG shapes animates as its eyebrows lift and lower repeatedly. The yellow circle head, eyes, and mouth are drawn using D3 selections with attributes like radius and position, while an arc path forms the smile. The eyebrows use D3's `transition().duration()` to shift vertically in a looping sequence. All shapes are centered via a translated group, with the example rendered entirely in SVG using d3.v5.