This example shows a horizontal bar chart of office supply sales, displaying the top 15 items with their unit counts. The visualization uses React to manage the component state and render the SVG elements, while D3 provides the data-loading and scaling utilities, including `csv`, `scaleBand`, and `scaleLinear`. The data is fetched from a GitHub Gist URL, and the bars are drawn as SVG `<rect>` elements with custom tick marks and labels for both axes.