This horizontal bar chart displays the 2020 population estimates for the top 30 countries, with countries listed along the y-axis and population values mapped to bar length on the x-axis. The visualization uses a linear scale for population and a band scale for country categories, rendering light green bars as SVG rectangles via the `d3.scaleLinear` and `d3.scaleBand` APIs. The bottom axis includes a custom tick format that converts millions to billions (e.g., "1.2B"), and both axes are labeled. Data is loaded asynchronously from a CSV file using `d3.csv`.