A choropleth map colors countries by their flight data from a TSV file, with a color legend and tooltip showing total flights, trip type, and aircraft. Using D3 v5 with `geoNaturalEarth1` projection and `geoPath`, it renders the world as SVG paths from TopoJSON. The map supports zoom via `zoom` and uses `scaleOrdinal` with `schemeRdBu` for color encoding. Hover events trigger a custom tooltip div, and `colorLegend` draws circles and text labels.