This example displays a bar chart of country populations, with each bar’s width fixed at 300 and height at 400 pixels. The chart is rendered as SVG elements using D3 v6, drawing rectangles via `svg.selectAll('rect').data(data).enter().append('rect')`. Population values are loaded from a CSV file using `d3.csv` and converted to numbers by multiplying by 1000. The current code only appends the rectangles without encoding data into visual attributes, leaving the bars uniform rather than proportional to population.