A bar chart displays the top 10 most populous countries for 2020, using horizontal rectangles without axes or labels. Built with React and D3 v5, the app loads data from the United Nations World Population Prospects via `d3.csv`, filters the first ten rows, and scales bar widths with `d3.scaleLinear`. The SVG rendering uses `d3.scaleBand` to position each country vertically, while React's `useState` and `useEffect` manage asynchronous data loading and render the final chart.