A smiling face built with D3.js demonstrates basic SVG manipulation and animation. The code uses `d3.select` and `d3.append` to construct circles for the eyes, rectangles for the eyebrows, and a path created with `d3.arc` for the mouth. A chained `transition().duration(2000)` moves the eyebrow group up and down repeatedly. The example renders entirely in SVG, centered within a 960×500 viewport, with static yellow fill and black stroke styling. No external data is loaded; the face is generated purely from hard-coded dimensions and offsets.