This example displays a world choropleth map colored by renewable energy levels, with a categorical color legend that allows users to click and filter countries by their energy level. The map uses SVG rendering with a Natural Earth projection, and the zoom interaction enables panning and scaling. The visualization is built with d3.js, using `d3.geoPath`, `d3.geoNaturalEarth1`, `d3.zoom`, and `d3.scaleOrdinal` for the color scale, while data is loaded from a TSV file and TopoJSON.