This example shows a bar chart of country populations using data loaded from a CSV file, with each country’s population value mapped to a rectangular bar. The bars are rendered as SVG rectangles with fixed width and height values of 300, so the visualization does not yet scale the bars to reflect the data magnitude. The code uses D3 v5’s `select` and `csv` methods to fetch the data, parse the population strings into numbers, and append the rectangles to an SVG canvas.