This area chart visualizes smartphone sales across multiple months, with distinct colored regions representing different product lines or years. The visualization uses stacked areas to show the cumulative contribution of each category over time, making it easy to compare relative proportions. Built with D3.js v7, the chart loads CSV data from a GitHub repository and uses d3.stack, d3.area, and d3.scaleBand to construct the stacked layout. SVG rendering handles the paths, axes, and rotated month labels, while a custom HTML legend with colored circles identifies each series.