This bubble chart shows the relationship between GDP and population for 20 global cities, with circle size encoding land area and color distinguishing cities. The visualization uses D3 v6 with SVG rendering, employing `d3.scaleLinear` for the x and y axes, `d3.scaleSqrt` for bubble radius, and `d3.scaleOrdinal` with `schemeCategory10` for color assignment. Interactive hover tooltips display city-specific population and GDP values, while axis labels identify the quantitative variables from the expanded_city_bubble_chart_dataset.csv file.