A Double object is an instance of the wrapper class Double, which wraps around a primitive double value and provides additional methods to manipulate and perform operations on that value.
A wrapper class is a class that provides an object representation for primitive data types. In this case, the Double class is the wrapper class for the double data type.
Autoboxing is the automatic conversion of a primitive data type to its corresponding wrapper class. For example, when assigning a primitive double value to a Double variable.
Unboxing is the process of converting an object of a wrapper class back to its corresponding primitive data type. This happens automatically when using an operator or method that requires a primitive value.