A horizontal bar chart displays the population of 30 countries in 2020, sorted by country name along the vertical axis. Population values are encoded as bar lengths using a linear scale, with green bars and blue tick lines against a white background. The chart is built with React and D3 v5, using `scaleBand` for the categorical y-axis and `scaleLinear` for the numeric x-axis. Data is loaded as CSV via the `csv` function, with population values multiplied by 1000, and axis labels are formatted using `format('.2s')` to show values in billions.