To understand the concept of the abstract class, let's discuss a few examples. When we draw a rectangle, we don't say that we have drawn a shape, we always use the name of that particular shape so that other people can understand what we mean. Similarly, if we are developing an application for an institute, we always create a student or teacher object. We don't need to create an object of the Person class, because person is a vague concept. Student, manager, or teacher, however, are concrete examples of a person. All concepts that are based on a general idea are known as abstract concepts. Classes that correspond to these abstract ideas are called abstract classes.