This visualization displays population trends over time for multiple world regions, using a line chart where each colored line represents a different region. Users can hover over the chart to select a specific year, which is marked by a vertical line and updates the visualization accordingly. The implementation uses D3 v5 with SVG rendering, employing scales like `scaleTime` and `scaleLinear`, the `line` generator with `curveBasis`, and a `nest` operation to group data by region. Data comes from UN population estimates and medium variant projections, processed with the `csv` loader.