This example visualizes world temperatures by coloring each country according to its latitude-derived temperature estimate, using a sequential blue-to-red scale. The map is rendered as SVG paths via `d3.geoPath` with a `d3.geoNaturalEarth1` projection, while country boundaries come from the `world-atlas@2` TopoJSON dataset. A linear gradient legend, built with D3's `scaleSequential` and `interpolateRdYlBu`, shows the temperature range from cold to warm.