This bubble chart visualizes 15 global cities by population (millions) on the y-axis, area (km²) on the x-axis, and population density as the bubble radius. Each circle is colored by region using `d3.scaleOrdinal` with `d3.schemeTableau10`. The code loads `globalCities.csv`, converts numeric fields, and renders SVG circles with `d3.scaleLinear` for both axes and `d3.scaleSqrt` for the radius. Axis labels and ticks are generated via `d3.axisBottom` and `d3.axisLeft`, with the chart drawn inside an SVG container.