This interactive visualization combines a bar chart and pie chart to explore religious demographics across the 20 most populous countries. Hovering over a country bar triggers an animated pie chart that breaks down that nation’s religious distribution, using d3.pie, d3.arc, and transition.attrTween for the sweeping animation. A colorLegend component maps religion categories to a d3.scaleOrdinal with schemeGreens colors. Data comes from Pew Research’s Global Religious Landscape, processed into a CSV and rendered as SVG. The bar chart uses d3.scaleBand and d3.scaleLinear to encode country population totals.