A face built from basic SVG shapes animates into a smile in this D3.js v5 example. Yellow circle head, black eyes, and rectangular eyebrows are drawn via `d3.select` and SVG attributes, then the smile uses the `d3.arc` generator. Transitions on the mouth and one eyebrow change their shape over two seconds, creating a cheerful expression. The other eyebrow remains static, showing asymmetric animation.