A stacked area chart visualizes the cumulative Quidditch points earned by each Hogwarts house across a series of matches. Using a step-after curve, the chart shows the contribution of Gryffindor, Slytherin, Ravenclaw, and Hufflepuff as layered areas, with an interactive legend identifying each house. The code uses d3.stack, d3.area, and d3.scaleOrdinal to generate the SVG rendering, with data aggregated from match records sorted by match number.