A pie chart is a type of chart, which is divided into slices to show their proportion compared to each other. For example, the students in a class who will study at different university programs next year: some are applying to a computer science program, some for medical sciences and some are applying to a social science program, etc. In order to visualize how large these groups are in relation to each other, the pie chart is divided into one slice per group, the central angle is proportional to the quantity of each group.