This choropleth map displays global economic classifications by country, with a color legend that doubles as an interactive filter. Clicking a legend item dims all countries except those matching the selected category, while hovering over the map highlights a country in red. The visualization uses D3 v5’s `scaleOrdinal` with a spectral color scheme and `geoPath` with the Natural Earth projection to render the map. Country boundaries and income data come from the world-atlas TopoJSON, and spatial interaction is handled by D3’s `zoom` event system.