This example presents two interactive pie charts that compare English Wikipedia page views by device type (mobile web, mobile app, and desktop) for two selected months. Users can advance the left chart’s month using arrow buttons or an auto-playing animation, while hovering over any slice displays a tooltip with its precise count. The visualization is built with D3.js v4, using `d3.pie` for slice geometry, `d3.arc` for rendering paths, and an ordinal color scale. Data is loaded from a CSV file containing monthly totals from 2016 to 2022.