This bubble chart visualizes the correlation between GDP per capita, life expectancy, and population-area ratio for 20 countries. Each circle represents a country, with its x-axis position reflecting GDP per capita, y-axis position reflecting life expectancy, and bubble size proportional to population density. The chart uses D3.js v7 with the `scaleLinear` API for axis and bubble scaling, and the `scaleOrdinal` API for color assignment. Interactive tooltips display precise country data on hover, while an SVG-based legend identifies each nation’s color.