This visualization shows the estimated religious breakdown of the 20 most populous countries in 2010, using stacked bars where each segment represents a religion’s population. The chart uses D3’s `stack()` and `flatRollup()` to structure the data, with `scaleOrdinal` and `schemeCategory10` for colors. Hovering over the color legend highlights that religion across all bars via `mouseenter` and `mouseleave` events, dimming other segments. Data originates from the Pew Research Center’s Global Religious Landscape report.