This pie chart visualizes the distribution of YouTube subscribers by country for the top 10 most-subscribed channels, based on data from a CSV file listing creators, subscriber counts, and country. D3.js v7 is used with `d3.csv` to load and parse the data, `d3.rollup` to aggregate subscriber totals by country, and `d3.pie` with `d3.arc` to generate the pie slices. A categorical `d3.scaleOrdinal` with `d3.schemeCategory10` colors each country, and labels are positioned using `labelArc.centroid`. An SVG legend lists countries with formatted subscriber counts.