The parent is more confused than you are, I think. I have almost never seen an histogram with bins of unequal sizes. The claims were dubious so I checked Wikipe

The parent is more confused than you are, I think. I have almost never seen an histogram with bins of unequal sizes. The claims were dubious so I checked Wikipedia, which mentions this: > The bins (intervals) must be adjacent and are often (but not required to be) of equal size. And this: > A histogram is used for continuous data, where the bins represent ranges of data, while a bar chart is a plot of categorical variables. To be fair, there probably are variations in nomenclature across fields. But saying that a histogram with bins of equal width is a bar chart is wrong, at least in the general sense.