This bar chart displays the top 10 most populous countries using data from the United Nations World Population Prospects 2019. The visualization uses React and D3 v5, with SVG rendering for the marks and axes. Population values are formatted in billions using D3’s `format` function, while `scaleBand` and `scaleLinear` position the bars. Hovering over each bar reveals a tooltip with the population figure via the native SVG `title` element.