This choropleth map colors countries by their economic classification, using a spectral color scale. The visualization loads population data from a CSV and world map geometry from TopoJSON, joining them by country ID. The map is rendered as SVG paths using `d3.geoPath` with a Natural Earth projection, and includes a custom color legend built with `d3.scaleOrdinal`. Hovering highlights a country in red, while pan and zoom are enabled through the `d3.zoom` API.