A horizontal bar chart displays the top 20 countries by 2010 population, using a CSV dataset loaded via D3's `csv` function. The chart is rendered as SVG with React components, mapping country names to a `scaleBand` y-axis and population values to a `scaleLinear` x-axis. Data values are formatted with D3's `format` function, converting values into billions with a 'B' suffix. Hovering over each rectangular bar reveals a tooltip with the population value, while blue tick lines and green bars provide clear visual separation.