This bar chart displays the top 10 most populous countries for 2020, using horizontal bars to compare population sizes. The chart is built with React and D3 v5, using `scaleBand` for the categorical y-axis and `scaleLinear` for the population x-axis. Data comes from the United Nations World Population Prospects 2019, loaded via D3's `csv` function. The SVG rendering includes custom axes and marks, with tooltips formatted using D3's `format` function to show values in billions.