This example demonstrates how to customize both the x- and y-axes of a bar chart, using D3 v5 within a React framework. The chart displays population data by age band, sourced from a local CSV file, and renders bars as SVG rectangles with a steelblue fill. The y-axis uses `scaleBand` for categorical age ranges, while the x-axis uses `scaleLinear` with a custom tick format that abbreviates large numbers (e.g., converting "G" to "B" for billions) via `format('.2s')`. Axes are drawn with `axisLeft` and `axisBottom`, with their domain lines removed for a cleaner look, and custom labels and titles added as SVG text elements.