Heatmap is one of those terms that gets applied to a few different things, especially choropleths. I've also seen it applied to grids (like a hours of the day v

Heatmap is one of those terms that gets applied to a few different things, especially choropleths. I've also seen it applied to grids (like a hours of the day vs day of the week, where each cell is how much X happened that hour).