Object name, property, and operation (method)

Class: a class is a collection of objects with the same properties and operations. Each class generally has an instance, and the class without an instance is an abstract class. Inheritance: inheritance refers to a mechanism by which different classes share properties and operations in the hierarchical Association of a class. For two classes a and B, if class A is a subclass of class B, then class B is a generalization of class A.