This example shows a horizontal bar chart ranking the top 20 countries by 2020 population, rendered as SVG rectangles in React. The code loads data from a CSV of UN population statistics using `d3.csv`, then uses `scaleBand` for the categorical country axis and `scaleLinear` for the population values. React’s `useState` and `useEffect` manage the asynchronous data loading, while JSX maps each country to a `<rect>` element. The chart updates purely through React’s render cycle, with D3 providing only scales and data parsing utilities.