This example visualizes the top 10 countries by 2020 population as a horizontal bar chart rendered with SVG. The code loads UN population data from a CSV file using `d3.csv`, processes the rows, and stores the result in React state via the `useState` and `useEffect` hooks. D3’s `scaleBand` and `scaleLinear` position the bars, while React maps the data to `<rect>` elements. A loading message displays until the data arrives, with the chart updating once React state is set.