A horizontal bar chart displays the top 10 most populous countries from the UN World Population Prospects 2019 dataset. The chart renders as an SVG using React components, with each bar’s length proportional to the 2020 population estimate. D3’s `scaleBand` and `scaleLinear` APIs position the categorical country labels and numeric population axis, respectively, while `.ticks()` generates gridlines and tick labels. A loading state is shown from React’s `useEffect` until data is fetched via D3’s `csv` parser.