This example demonstrates how to build a simple bar chart from a CSV dataset of country populations, initially rendering all rectangles with fixed dimensions. The code uses D3 v5’s `scaleLinear` to later map population values to bar widths, while the `csv` method parses the data file and converts population strings to numbers. SVG elements are created via a data join with `selectAll('rect').data().enter()`, though the current implementation only appends static rectangles without encoding data values.