This line chart displays population over time by world region, with each region represented by a colored path and a color legend. The visualization allows selection of a specific year by clicking on the chart, which updates the display accordingly. Built with D3 v6, the chart uses `scaleTime` and `scaleLinear` for axes, `line` with `curveBasis` for smooth paths, and `scaleOrdinal` with `schemeCategory10` for colors. The data comes from UN population estimates, processed by melting wide-format CSV data into tidy rows.