This bar chart displays the top 10 countries by 2020 population from a UN Population dataset loaded via `d3.csv`. It uses React with hooks (`useState`, `useEffect`) to fetch and store the data, then renders SVG rectangles scaled by `d3.scaleBand` for countries and `d3.scaleLinear` for population values. Gridlines and axis ticks are generated with `xScale.ticks()`, and the chart is drawn within a margin-based layout.