A horizontal bar chart displays the populations of twenty countries from 2010, using a responsive React component with SVG rendering. D3 v5 scales (`scaleBand` and `scaleLinear`) position the bars, while custom `AxisBottom` and `AxisLeft` components format tick labels with SI prefixes (e.g., "B" for billions). The `Marks` component adds native SVG `<title>` tooltips, and data loads asynchronously via `d3.csv` from a GitHub-sourced CSV file where population figures are multiplied by 1,000. Green rectangular marks encode values along the x-axis, with styled tick lines and text for visual clarity.