This bar chart visualizes the top 30 countries by population in 2020, sourced from a CSV file. Using D3 v5 within a React framework, the code employs `scaleBand` and `scaleLinear` for axis mappings and renders bars as SVG rectangles. The chart includes custom tick formatting via `format('.2s')`, converting values to billions with a 'B' suffix, and a tooltip showing the formatted population value on hover.