This choropleth map visualizes GDP per capita (PPP, current international $) by country, using data from the World Bank’s 2020 dataset. It renders countries as geographic paths via `d3.geoPath`, fills them with a sequential color scale (`d3.scaleQuantile` and `schemeYlGnBu`), and marks missing values in gray. The code fetches TopoJSON world atlas boundaries and a CSV dataset, then combines them using `topojson-client` and `d3.csvParse`. Natural Earth projection and graticule lines provide geographic context.