This chart displays population over time by region, with multiple colored lines showing changes from 1950 to 2100. A legend on the right identifies each region. The visualization uses d3.line with curveBasis for smooth paths, d3.scaleTime and d3.scaleLinear for axes, and d3.nest to group data by region. Data comes from UN population estimates and medium variant projections, processed through a custom melt function. The color legend is rendered using a custom colorLegend module.