This interactive bubble chart visualizes global population data by country, with circles sized proportionally to population and colored by continent. Users can toggle between four grouping modes—combine all countries, group by continent, place circles at country center coordinates, or scale by population—and switch between solid colors and country flag patterns. Built with D3 v4, the visualization uses `d3.forceSimulation` with custom force configurations for each layout, while transitions animate the bubbles when switching groupings. Hovering reveals country names and population counts, and a color-coded continent legend slides into view when relevant.