Categorization is a mental and intellectual process in which objects and ideas are recognized, understood, compared to and differentiated from one another. This process identifies the ways in which two or more objects are alike, and how they are different from one another and can be grouped with other similar objects. For instance, if a person was seeing a whale for the first time, they would probably believe it was a fish because it has fins, swims and lives underwater like a fish. However, with further observation and study it would be noted that unlike a fish, it breathes air and nurses its young, characteristics that identify it as a mammal. With the combination of these traits, it would have be categorized as a mammal that lives in water like dolphins and porpoises.