This bar chart visualizes the top 10 most populous countries using data from the United Nations World Population Prospects 2019. Each horizontal bar represents a country, with population values formatted in billions. The visualization uses React with D3 v5 scales (scaleBand and scaleLinear) for layout, and renders SVG rectangles. Axis components are custom-built, and a native SVG `<title>` element provides tooltips showing population values.