This pie chart visualizes user behavior classes derived from mobile app usage data, categorizing users into five levels from “Minimal User” to “Addicted User.” The visualization loads a CSV dataset via `d3.csv` and uses `d3.rollup` to count occurrences per class, then renders animated SVG slices with `d3.pie` and `d3.arc`. Slice labels display percentages, while hover interactions shift slices outward using `arc.centroid` and `transition.attrTween`. A legend with `d3.scaleOrdinal` and `d3.schemeSet2` maps colors to behavioral categories.