Fifteen circles animate in a wave-like pattern across the screen, their vertical positions and radii oscillating sinusoidally over time. The visualization uses D3 v6’s `selectAll`, `data`, and `join` methods to bind and update circle elements on an SVG canvas, with a `setInterval` driving the animation at 60fps. Data is generated procedurally via `range` and trigonometric functions, demonstrating the core update pattern of D3’s data-join without explicit enter or exit handling.