This example shows a horizontal bar chart of the top 10 countries by 2020 population, using React state to manage the data and D3 scales to position the bars. It loads the un-population CSV via `d3.csv`, maps the population values, and renders SVG rectangles with `scaleBand` and `scaleLinear`. Grid lines and tick labels are generated from `xScale.ticks()`. The chart uses React hooks (`useState`, `useEffect`) to fetch and update the data, with D3 v6 providing the scaling and CSV parsing utilities.