This visualization displays the populations of 30 countries for 2020 as a horizontal bar chart, with each bar’s length proportional to its population value. Built with React and D3 v5, the app uses `d3.scaleBand` for the categorical y-axis, `d3.scaleLinear` for the continuous x-axis, and custom React components (`AxisBottom`, `AxisLeft`, `Marks`) to render SVG rectangles. The data is loaded from a remote CSV via `d3.csv` and formatted with `d3.format` for tick labels.