This visualization explores the relationship between a selected audio feature and song popularity using Spotify track data. Users can switch among features like danceability, energy, and valence via a dropdown, and adjust the number of bins with a slider. The chart combines a bar chart of average popularity with a lower panel showing track counts, colored by loudness and duration using d3 scales. The React app uses d3.rollups, d3.pairs, and scaleBand/scaleLinear to aggregate and render the SVG with animated transitions.