This heatmap displays average song popularity across music genres and years from 2010 to 2019, using a light-to-dark blue sequential color scale. It loads Spotify data from a CSV file, groups entries by genre and year, and computes mean popularity values with d3.group and d3.mean. The visualization uses d3.scaleBand for axes, d3.scaleSequential with interpolateYlGnBu for color encoding, and d3.axisBottom and d3.axisLeft for labels. Hover interactions reveal exact values via a dynamic tooltip.