This example displays a static bar chart of country populations, reading from a CSV file with `d3.csv` and rendering rectangles with `d3.selectAll` and `data.join`. It uses D3 v7 within a plain HTML page, with data loaded asynchronously and converted to numbers. The visualization demonstrates basic data binding and SVG shape creation, though the rendered bars are all fixed at 300 by 300 pixels, so the chart does not reflect population values visually.