Because you will know how many students failed, how many of them got good grades etc the moment you look at the histogram.
For example, if you want to create a histogram from the result scores of the students in a class, you can assess the performance of the class at a glance. The number and height of the bars are proportional to the number of different ranges called bins and to the frequency of data within those bins. It is a graph with a series of rectangular bars. A histogram shows the frequency of data in different intervals within the data range.
