A smiling yellow SVG face with animated eyebrows demonstrates basic D3 shape and transition techniques. The face is centered using SVG groups and transforms, with circles for eyes, rectangles for eyebrows, and a path generated by D3’s `arc` function for the mouth. The eyebrows move upward and return via chained `transition().duration()` calls. The example uses d3-v5 select and arc APIs to build the static face and animate its expressions purely through SVG attribute interpolation.