The subclass relation imposes a hierarchy relation on the set of all classes. If multiple inheritance were allowed, the subclass relation would impose a partial order on the set of all classes. Members A class typically contains a set of members , which can be variables, functions, etc. Members are classified as either instance or global members. Instance members become properties of instances of the class.
Members can have attributes which modify their behavior.
An instance may also have additional dynamic properties , which can be added and deleted any time after the instance has been created. Unless specified otherwise, each separately created instance has a distinct identity. Instances provide the appearance of lasting forever, although an implementation is expected to garbage-collect them when they are no longer reachable. Properties A property is a runtime binding of a property name to a value. The values of some properties can change.