Instance vs Object

An object is a software bundle of related state and behavior. A class is a blueprint or prototype from which objects are created. An instance is a single and unique unit of a class.

When an object of class A is created, that object is an instance of class A. if you write

A a = new A();

then a is a variable that refers to an object of type A, a is not an object itself. We use a to access the object it refers to.