This line chart displays population trends for selected countries from 1950 to 2020, using a color-encoded line for each nation. The visualization is built with the Vega-Lite API (vl) on top of Vega and Vega-Lite, rendering to SVG. Data is fetched as CSV via d3.csv from a remote gist, then unfolded into long format with Year and Population fields. Tooltips, provided by Vega-Tooltip, show the country name on hover, while a custom config adjusts axis and label styling.