This example demonstrates how D3 selections bind data to SVG elements. It renders five circles across the viewport, each with a random radius between 10 and 50, generated by a custom `Data` function using `d3.range`. The `Circles` module applies a re-usable selection pattern with `selectAll`, `data`, and `join` to create and style the circles. The main script uses `d3.select`, appends an SVG sized to the window, and calls the circle component, showing a modular approach to D3 v7 development in an ES modules setup.