An animated smiley face demonstrates fundamental DOM manipulation and transitions with D3.js v5. The face consists of SVG shapes, including a circle, eyes, rectangular eyebrows, and a path-based mouth. The eyebrows move up and down using chained `transition().duration()` calls. The code imports `select` and `arc` from D3, uses the `svg` selection to set up the coordinate system, and generates the mouth path with the `arc` API.