This choropleth map displays worldwide brain and nervous system cancer deaths for 2019, using a yellow-to-red sequential color scale to indicate mortality counts per country. It renders geographic boundaries from the World Atlas TopoJSON file via `d3.geoPath` and `d3.geoNaturalEarth1`, joining country codes with a CSV dataset. Hovering over a country appends its name and death total to a div, while a legend built with `d3.scaleSequential` and `interpolateYlOrRd` shows the color range.