This example visualizes the top 10 countries by 2019 population using a horizontal bar chart rendered with React and D3 v5. It shows population values as bar lengths on an SVG canvas, with country names on the y-axis and numeric ticks on the x-axis. The code loads CSV data via `d3.csv`, then uses `scaleBand` and `scaleLinear` to map countries and populations to pixel coordinates. Gridlines and axis labels are manually generated using `xScale.ticks()`, while bars are drawn as SVG `<rect>` elements. The visualization updates reactively via React's `useState` and `useEffect` hooks.