A Sankey diagram visualizes the flow of values between interconnected processes, with circular links rendered as red curved paths to highlight feedback loops where data returns to earlier stages. Built with React and D3 v4, the example uses the d3-sankey-circular library to compute node positions and circular path data, while SVG with animation displays the links. Hover interactions dim non-adjacent nodes and links, and the diagram uses a sequential color scale for node coloring.