What is meant by Histograms and where and why use it?

A histogram is a bar graph of raw data that creates a picture of the data distribution. The bars represent the frequency of occurrence by classes of data. A histogram shows basic information about the data set, such as central location , width of spread , and shape. Use histograms to assess the system’s current situation and to study results of improvement actions. The histogram’s shape and statistical information help you decide how to improve the system. If the system is stable, you can make predictions about the future performance of the system. After improvement action has been carried out, continue collecting data and making histograms to see if the theory has worked.