This pie chart visualization displays website traffic by source, measured in thousands of visitors, with each slice labeled directly on the chart and accompanied by a color-coded legend. The code uses D3 version 6, specifically the `d3.pie()` layout function, `d3.arc()` for defining the pie geometry, and `d3.scaleOrdinal` with `d3.schemeCategory10` for categorical coloring. Data is loaded asynchronously from a raw GitHub Gist CSV file via `d3.csv()`, with each visitor value converted to a number before being passed to the pie layout. The visualization renders as SVG, with arcs drawn using `path` elements and centroid-based text labels, while the legend is constructed separately using `rect` and `text` elements positioned on the right side of the chart.