This visualization displays the top 20 countries by reported coronavirus cases, rendered as horizontal bars in an SVG chart. The application uses React hooks such as `useState` and `useEffect` to asynchronously load and process CSV data via D3’s `csv` method. The chart encodes population counts along a linear scale (`d3.scaleLinear`) for the x-axis and country names on a band scale (`d3.scaleBand`) for the y-axis. Custom grid lines and tick labels are drawn manually, with rectangle marks filled green via CSS.