histogram

In statistics, a graph showing frequency of data, in which the horizontal axis details discrete units or class boundaries, and the vertical axis represents the frequency. Blocks are drawn such that their areas (rather than their height as in a bar chart) are proportional to the frequencies within a class or across several class boundaries. There are no spaces between blocks.

If all the columns have the same width, then the element that appears most frequently (the mode) is represented by the tallest column. If the columns are of different widths the areas must be compared. Total frequency can be calculated by adding together the areas of all the columns.