This horizontal bar chart visualizes the 2020 populations of 30 countries. Built with React and rendered as SVG, it uses D3’s `scaleBand` for the categorical y-axis and `scaleLinear` for the quantitative x-axis. The `Marks` component draws rectangles whose widths correspond to population values, with tooltips formatted via D3’s `format` function. Axis tick labels are formatted with the `.2s` specifier to show values in billions, and data is loaded from a remote CSV using D3’s `csv` function within a custom `useData` hook.