This visualization shows population over time by region, with multiple line paths drawn in a single SVG chart. The lines are grouped by region name and displayed with a categorical color scale, accompanied by a legend. Data comes from UN population estimates and medium variant projections, melted into tidy format with `d3.csv`. The chart uses `d3.scaleTime`, `d3.scaleLinear`, `d3.line`, `d3.axisLeft`, `d3.axisBottom`, `d3.group`, and `d3.scaleOrdinal` to render axes, lines, and legends with SVG.