A horizontal bar chart displays population estimates for 30 countries in 2020, sourced from a CSV file loaded via `d3.csv`. The React-based visualization uses `d3.scaleBand` for the categorical y-axis and `d3.scaleLinear` for the numeric x-axis, with SVG rectangles rendered by the `Marks` component. Axes are built with custom `AxisBottom` and `AxisLeft` components, and tooltips use the native SVG `<title>` element. The x-axis labels are formatted using `d3.format` to abbreviate large numbers, converting 'G' to 'B' for billions.