This example shows a React-based world map visualization where hovering over a country highlights it in red. The map is rendered as SVG using D3’s geographic projection and TopoJSON for country boundaries. The code also includes a scatter plot of fertility rates against cluster categories, built with d3.scaleBand and d3.scaleLinear, though the map interaction remains the primary focus. Data comes from a CSV file, and the interaction relies on CSS hover states rather than D3 event handlers.