D3.js draws a smiling face using basic SVG shapes, then animates the eyebrows through a continuous transform transition. The example demonstrates fundamental DOM manipulation with `select` and `append` to construct circles, rectangles, and paths from `d3.arc` for the nose and mouth. Eyebrows move via chained `transition().attr()` calls, illustrating timed attribute changes on SVG elements in a 960x500 viewport.