This visualization displays the population of the top 30 countries in 2020 as a horizontal bar chart. Population values, read via `d3.csv` from a remote GitHub dataset, are formatted with `d3.format` and converted from raw values to millions. The chart is built with React, rendering SVG rectangles for each bar, with axes generated by custom `AxisBottom` and `AxisLeft` components using `d3.scaleBand` and `d3.scaleLinear`. A tooltip, implemented as an SVG `<title>` element, shows the formatted population on hover. The axis tick marks and labels are styled with CSS, and the x-axis is labeled "POPULATION-2020."