This visualization displays average movie revenue per genre and year as a heatmap using D3 v7. The code builds a grid of colored rectangles from CSV data via `d3.csv` and `d3.rollups`, with a sequential color scale using `d3.scaleSequential` and `d3.interpolateRgb`. A gradient legend with an axis accompanies the SVG chart, and two buttons let viewers reorder rows alphabetically or by row mean using `d3.axisLeft` and `d3.axisBottom`. The data comes from a gist-hosted CSV file.