This horizontal bar chart displays the population of the top 10 most populous countries, based on 2018 estimates from the United Nations World Population Prospects. The visualization loads data from a CSV file using `d3.csv`, then renders SVG bars with `d3.scaleBand` for the categorical country axis and `d3.scaleLinear` for the population values. Axis labels and tick formatting use `d3.axisLeft`, `d3.axisBottom`, and `d3.format` to abbreviate population numbers in billions. The chart includes a title, axis label, and custom margins.