A bar graph is a graphical representation of a frequency distribution of a categorical data. It is made of rectangular bars and each bar represents a category and its frequency in a data set. A bar graph is most often created using the data in a frequency table. A bar graph can be oriented either horizontally or vertically by swapping which axis shows the categories and which contains the frequency of each category. For example, consider a group of students who are asked what their favorite color is. The categories and values will be adjusted accordingly. The graphical representation of a frequency distribution for numerical data is called a histogram.