This interactive line chart displays global population trends across regions from 1950 to 2100, with a vertical marker indicating the currently selected year. Users hover over the chart to update the marker and select a new year. The visualization uses D3 v5’s `scaleTime`, `scaleLinear`, `nest`, and `line` with `curveBasis`, rendering in SVG. Data comes from UN population estimates and medium-variant projections, processed via CSV loading and a custom melt function.