This interactive stacked bar chart visualizes the estimated 2010 religion breakdown of the world's 20 most populous countries, using D3.js version 3.5.5 to render SVG graphics with animation. The chart displays layered bars across countries, with hover tooltips powered by the D3-tip library revealing specific religion populations, while hovering over the color legend highlights individual religions by fading the other bars. The x-axis uses a custom tick format that converts large numbers to abbreviated forms like "B" for billions. Data originates from Pew Research's Global Religious Landscape, processed through a custom script.