This visualization shows global population trends from 1950 to 2100, using multiple lines to compare different development groups. A vertical reference line marks the year 2018, and a color legend identifies each series. The chart is built using D3 v5, with data loaded from two CSV files and melted into a tidy format. It uses `d3.scaleTime`, `d3.scaleLinear`, and `d3.line` to render the line paths, with axes generated by `d3.axisLeft` and `d3.axisBottom`.