This heatmap visualizes the monthly popularity of GPUs on eBay, using color intensity to represent the number of units sold for each GPU model across several months. The darker orange cells indicate higher sales volumes, while lighter cells show lower activity. The data is loaded from a CSV file using D3 v7, and the visualization is rendered as an SVG. The code employs `d3.scaleBand` for the x and y axes, `d3.scaleSequential` with an orange interpolator for color encoding, and tooltips to display the exact sold count on hover.