This choropleth map displays world countries colored by income group, with an interactive color legend that filters the map when clicked. Hovering reveals country names and values via tooltips. Built with D3 v5, it uses `d3.geoPath` with the Natural Earth projection and `d3.scaleOrdinal` with the Spectral scheme. The data comes from the World Atlas TopoJSON and TSV files, and the code employs `d3.select`, `d3.event`, and a `zoom` function for panning and zooming.