A horizontal bar chart displays the top 10 most populous countries, with bars sized by population using an SVG `<rect>` for each mark. Built with React for component state and rendering, it uses D3 v5 scales (`scaleBand`, `scaleLinear`) and formatting (`format`) to position bars and tick labels. The bar widths encode population values, and hover tooltips show formatted numbers. Data comes from the United Nations World Population Prospects 2019 CSV, loaded asynchronously via `d3.csv` and sliced to the top ten entries.