This stacked bar chart visualizes the estimated 2010 religious breakdown of the 20 most populous countries, using data from the Pew Research Center. The chart shows the population of each country divided into colored segments by religion. Users can hover over individual bars to see exact figures via tooltips, or hover over the legend to highlight specific religious groups within the visualization. The implementation relies on D3.js version 3.5.5, leveraging d3.svg.axis, d3.layout.stack, and d3.legend.color APIs to construct the chart and its interactive elements.