This choropleth map visualizes global income groups by country, using a spectral color scale to differentiate categories. Built with D3 version 5, the map employs `d3.geoNaturalEarth1` for projection and `d3.geoPath` to render country boundaries from TopoJSON data, with attributes joined from a TSV file. The visualization supports zoom interactions via `d3.zoom`, displays hover tooltips with country names and income groups, and includes a custom color legend rendered from SVG circles and text.