A bar chart displays the top ten countries by 2020 population from a UN dataset, loaded via D3’s `csv` utility and rendered as SVG rectangles. The visualization uses React’s `useState` and `useEffect` hooks to fetch and parse the data, while D3’s `scaleBand` and `scaleLinear` map country names and population values to pixel coordinates within a fixed margin. The chart updates once data arrives, initially showing a loading message in a `<pre>` element.