What is the mean of object identity and classification in terms of object oriented programming?

Answer 1

Well, that's pretty straightforward. An "object" is a named thing with certain properties, like in Plato's "Allegory of the Cave," and "classification" refers to a GROUP of similar things, that all share certain properties. To use a non-programming example, the classification "animals" might include objects like "mammal," "reptile," "bird," and so forth. Or those things might themselves be "classes," depending on your own personal choices and needs. So a "bird" might be a "class" including "objects" like "robin," "thrush," and "starling," with properties like "color of breast," "forked tail," and "temperament."