This bar chart displays the top 20 countries by population in 2010, with countries listed alphabetically on the y-axis and population values on the x-axis. Built with React and D3 v5, the visualization uses `scaleBand` and `scaleLinear` to map the data, rendered as SVG rectangles. Population values are formatted using `format('.2s')` to display billions. Data is loaded from a CSV file using `d3.csv` in a custom `useData` hook, with hover effects changing bar colors and tooltips showing exact population values.