A bar chart displays the top 10 countries by 2020 population, loaded from a UN dataset via `d3.csv`. React's `useState` and `useEffect` manage the asynchronous data fetching, while `d3.scaleBand` positions bars on the y-axis and `d3.scaleLinear` maps population values to widths. The SVG rectangles render through React components, with `d3.max` setting the x-domain.