This D3.js bubble chart plots 50 countries by GDP per capita on the x‑axis and life expectancy on the y‑axis. Each circle’s area is proportional to population, and color encodes geographic region. Hovering highlights a bubble and shows a tooltip with exact country statistics. The visualization uses `d3.scaleLinear` for axes, `d3.scaleSqrt` for bubble radius, `d3.scaleOrdinal` with `d3.schemeCategory10` for colors, and SVG for rendering.