This example shows a grouped bar chart comparing population data from 1980 and 2023. The visualization encodes data using color and bar height, with tooltips revealing exact population values on hover. The code uses D3 v6 with SVG rendering and animation, leveraging d3.json for data loading, d3.scaleBand and d3.scaleLinear for positioning, and d3.axisBottom/d3.axisLeft for axes.