This bar chart displays the top 10 most populous countries using United Nations World Population Prospects 2019 data, with population values converted to billions. Built with React and D3 v5, it uses `scaleBand` for the categorical y-axis, `scaleLinear` for the population x-axis, and SVG `<rect>` elements rendered by the `Marks` component. The chart includes formatted tick labels via `d3.format` and interactive tooltips using SVG `<title>` elements.