This example demonstrates fundamental DOM manipulation with D3.js by building a smiling face whose eyebrows animate up and down. It shows how to select an SVG element, append grouped shapes—circles for the face and eyes, rectangles for eyebrows, and a path for the mouth—and position them using translation transforms. D3’s `transition().duration()` chains move the eyebrows vertically over two seconds, while the mouth uses `d3.arc()` to create a curved smile. The code imports `select` and `arc` from D3 v5 and renders entirely in SVG.