A bar chart displays the top 10 most populous countries, with horizontal bars representing each country's 2019 population. The chart uses React's `useState` and `useEffect` hooks to load CSV data via `d3.csv`, then renders SVG marks directly in JSX. D3's `scaleBand` and `scaleLinear` position bars, while tick marks and grid lines are drawn manually using SVG elements. The data comes from a GitHub-hosted CSV file, and bars are colored with a default dark tone.