This example visualizes religious populations across countries from a CSV file, displaying each country’s data as rectangles in an SVG. It uses D3 v5’s `csv` loader to parse the data, converts population values to numbers, and appends rectangles via `selectAll` and `data` binding through the `enter()` selection. The `scaleLinear` is configured but not applied, leaving the rectangles fixed at 300 by 300 pixels. The visualization demonstrates basic data loading and SVG element creation without implementing axes or dynamic scaling.