This example demonstrates the initial step of building a bar chart with D3, loading population data from a CSV file and rendering static rectangles for each country. The bars are drawn as SVG rectangles with fixed width and height, and the population values are parsed and multiplied by 1,000. It uses `d3.csv` to load the data, `d3.select` to target the SVG, and the `enter` selection to append the rectangles. Styling is minimal, with no axes or scales applied yet.