A horizontal bar chart displays the top ten countries by estimated 2020 population, loaded from a CSV file using the `d3.csv` utility. React manages the application state with the `useState` and `useEffect` hooks, while D3’s `scaleBand` and `scaleLinear` map country names and population values to screen coordinates. Each bar is an SVG `<rect>` element rendered by React, with its width proportional to population and its height set by the band scale’s bandwidth.