This visualization shows global population trends over time, with multiple colored lines representing different regions across the years 1950 to 2100. It uses a line generator with curveBasis interpolation to create smooth paths, with data melted from separate UN population estimate datasets for historical and projected figures. The chart employs d3.scaleTime, d3.scaleLinear, and d3.scaleOrdinal for axes and color encoding, while a custom colorLegend function renders the categorical legend. Axis grids with tick lines and formatted tick labels using d3.format provide readable comparisons between regions.