This visualization displays population trends over time for multiple regions, with each region represented by a colored line. A vertical line marks the currently selected year, and hovering over the chart updates this selection. The view includes an ordinal color legend using `d3.scaleOrdinal` with `schemeCategory10`. Data is loaded via `d3.csv` from UN population estimates, processed through a custom melting function, and rendered using `d3.line` with `curveBasis` and SVG paths. Interactive mouse events trigger year selection.