This example displays a choropleth map of HIV/AIDS prevalence among adults aged 15–49 for the year 2017, using a sequential yellow-orange-red color scale to indicate infection rates. Country boundaries come from World Atlas TopoJSON, with graticules and interior borders rendered for visual polish. The React app loads CSV data on HIV prevalence and ISO country codes, joins them by numeric code, and projects the map using d3.geoNaturalEarth1 and d3.geoPath. Missing data appears in grey, and the visualization updates via d3.scaleSequential with interpolateYlOrRd.