A React and D3.js bar chart displays population data as horizontal bars using SVG. The visualization maps each country to a vertical band via `d3.scaleBand` and population to horizontal lengths with `d3.scaleLinear`, annotated by `d3.axisLeft` and `d3.axisBottom` axes. Data is loaded from a gist CSV file, then parsed and scaled, rendering steel blue rectangles inside a 960x500 SVG. The code uses D3 v5 imported as named modules, with selectors and attribute chaining to build the chart.