In computer science, cloning refers to the making of an exact copy of an object, frequently under the paradigm of instance-based programming, or object-oriented programming (OOP).
In most programming languages (exceptions include Ruby), primitive types such as double, float, int, long, etc.
simply store their values somewhere in the computer's memory (often the call stack).
By using simple assignment, you can copy the contents of the variable to another one: Copying primitive types in Java or C++: Many OOP programming languages (including Java, D, ECMAScript, and C#) make use of object references.
The process of actually making another exact replica of the object instead of just its reference is called cloning.