This example shows a choropleth world map coloring select countries by population, with interactive buttons to zoom into India or reset the view. It uses D3 v7 and TopoJSON to load world geography, projecting countries with d3.geoMercator and rendering them as SVG paths filled via d3.scaleSequential with an orange interpolator. Population values for India, the USA, China, Brazil, France, and Germany are drawn from an inline array and matched to country IDs. A d3 transition animates the map transform when zooming or resetting.