Abstraction allows the developer to separate objects so that they can work on different levels of detail more easily. For instance, if you are defining an object-oriented application to model a zoo, you can define a base class "animal", then derive "reptile", "mammal", "bird", and "fish" from it. The "animal" class implements the attributes and actions of all animals. Each of the derived classes refines those attributes and actions to a finer level of detail.
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This was first published in December 2002