This chart displays population over time by region, using multiple smoothed lines to compare trends from 1950 to 2100. The code uses d3.csv to load UN population estimates and a medium variant projection, then d3.nest to group data by region and d3.line with curveBasis to generate the paths. Axes are rendered with axisBottom and axisLeft, while a custom colorLegend function handles the categorical color scale. The visualization is drawn as an SVG with a title and axis labels.