This example demonstrates the "margin convention" in D3 by rendering the top 10 most populous countries as a simple bar chart, with visible spacing around the plot area. It uses React hooks to load and filter data from the United Nations World Population Prospects 2019 via `d3.csv`, then maps it to SVG rectangles with `scaleBand` and `scaleLinear`. The chart omits axes, drawing only the bars inside a translated `<g>` element, highlighting the margins as a foundational layout principle.