This chart shows the populations of 20 countries in 2010 as horizontal bars. React and D3 v5 are used to render an SVG visualization, with a band scale mapping countries to the y-axis and a linear scale for population values. Data is loaded from a remote CSV using `d3.csv`, and D3’s `scaleBand` and `scaleLinear` drive the layout, while `d3.format` with the `.2s` specifier formats tick labels and tooltips. Axes and marks are defined as React components, with custom tick styling for lines and text.