A horizontal bar chart displays the populations of the ten most populous countries, using data from the UN. The chart customizes the bottom axis by converting D3’s default SI-prefix formatting from “G” to “B” via `format('.3s')` and string replacement. It builds scales with `scaleLinear` and `scaleBand`, renders SVG rectangles for bars, and positions the axes using `axisBottom` and `axisLeft`. The visualization is generated with D3 v5 and styled with plain CSS.