This example shows a horizontal bar chart comparing 2020 populations for up to 30 countries, with each bar labeled by country and sized proportionally to its population. The chart uses an SVG rendering with a green fill for bars and blue tick lines, and hover tooltips formatted with abbreviations like "B" for billions. Built with React and D3 v5, it employs `scaleBand` for the categorical y-axis, `scaleLinear` for the numeric x-axis, and `csv` to load data from a remote gist URL. Axis components (`AxisBottom`, `AxisLeft`) and `Marks` are custom React components that generate tick lines and rectangular marks, while `format('.2s')` handles tick label abbreviation.