This bar chart displays the population of countries in 2015, with bars sorted in descending order and colored by country. It is built using the Vega-Lite API, which programmatically defines the visualization specification, while D3.js loads the CSV data from a Gist. The chart is rendered as SVG via Vega and Vega-Lite, with tooltips enabled through vega-tooltip and a custom config to adjust axis and label styling for readability.