Object: A single THING or concept, either in a model of an application domain or in a software system that can be REPRESENTED as an encapsulation of state, BEHAVIOR and identity, a member of a class that defines a SET of similar objects.
Class: A class is a descriptor for a collection of objects that are logically similar in terms of their behavior and the STRUCTURE of their data.
Instance: A single object, usually called an instance in the context of its membership of a particular class or type.

Object: A single thing or concept, either in a model of an application domain or in a software system that can be represented as an encapsulation of state, behavior and identity, a member of a class that defines a set of similar objects.
Class: A class is a descriptor for a collection of objects that are logically similar in terms of their behavior and the structure of their data.
Instance: A single object, usually called an instance in the context of its membership of a particular class or type.