A heat map visualizes weekly Broadway show attendance by month and year, with each cell shaded from yellow to red according to the number of attendees. Hovering a cell reveals a tooltip displaying the specific year and month. The visualization uses D3.js v7 to load CSV data, build band scales for the month and year axes, and apply a sequential color scale with the YlOrRd interpolator. The axes are labeled to clarify that months appear on the y-axis and years on the x-axis.