This bar chart visualizes the population of 20 countries in 2010, sorted by country name. Each bar’s length corresponds to population, with hover tooltips showing formatted values in billions. The visualization is built with React and D3 v5, using `scaleBand` for the y-axis, `scaleLinear` for the x-axis, and custom `AxisBottom`, `AxisLeft`, and `Marks` components to render SVG rectangles and tick marks. Data is loaded from a CSV file via `d3.csv`.