This choropleth map colors countries by their economy classification using an ordinal color scale based on `d3.scaleOrdinal` and `d3.schemeSpectral`. The visualization also includes an interactive color legend, built with reusable D3 components, that allows users to filter countries by clicking on a category. Geographic boundaries are rendered as SVG paths using `d3.geoPath` with a natural Earth projection, while the data comes from the World Atlas TopoJSON and TSV datasets. Zooming is enabled through `d3.zoom`, and hovering highlights individual countries.