Class, Object, Instance

Class

• A blueprint or template for creating objects
• A collection of related variables and methods

Object

• An entity to be implemented in the software
• An instance created exactly as defined by the class
• It is also called an instance of a class.
• The term "object" has a broader meaning that represents all instances.
• From an OOP perspective, it is called an "object" when declared with a class type.

Instance

• A concrete entity implemented in the software world based on a blueprint.
• In other words, when an object is materialized in software, it is called an "instance."
• The materialized instance is allocated in memory.

Feature

• An instance can be considered a subset of an object.
• From an OOP perspective, when an object is allocated in memory and actually used, it is called an instance.
• The term is used when focusing on the relationship between an abstract concept (or specification) and a concrete object.