How is a histogram constructed and how does it differ from a frequency polygon ?

While constructing histogram, the size of the items and their frequencies are represented in the form of rectangles. Each class is represented by a distance on the scale on X-axis and their respective frequencies are drawn on Y-axis. The heights of the bar is a measure of concentration of frequency.

Histogram presents a frequency distribution arranged in class interval while frequency polygon is a graphical representation of a line joining the mid-values of the top of the frequency rectangles of histogram.