This bar chart visualizes the number of corona cases across the top 20 countries, using a horizontal layout where bar length corresponds to case counts. The visualization loads data from a CSV file via `d3.csv` and renders SVG elements using React. It employs `d3.scaleBand` for the categorical country axis, `d3.scaleLinear` for the numeric case values, and manually drawn gridlines and tick labels using D3’s scale methods. The title "Corona Cases" appears in the HTML header.