A histogram is a concept from statistics. It is a graphical display that tells us about the distribution of the samples involved. They are commonly a picture made from a table with many categories. The table tells how many samples there are in each category.
The word histogram is derived from histos and gramma in Greek. Histos means web or mast. Gramma means drawing, record or writing. A histogram of something is therefore, etymologically speaking, a drawing of the web of this something.