A smiley face rendered with SVG animates its eyebrows upward and downward in a looping transition. The example demonstrates fundamental D3.js DOM manipulation by selecting an SVG element, appending groups, circles, rectangles, and a path for the mouth using `d3.select` and `d3.arc()`. Eyebrow movement is driven by chained `transition().duration()` calls that alternate the group’s `transform` attribute. The code uses D3 v6, with dimensions defined by the SVG’s width and height attributes.