Pointer / Reference
A pointer or reference is the memory address of the beginning of a record or block of storage, which extends through higher memory addresses. On modern machines, a pointer is 64 bits or 8 bytes (48 bits actually used). On older machines, a pointer was the same size as int, 32 bits, but that can address only 4 Giga bytes of storage. (A byte is 8 bits.)
null is typically represented by a pointer value of 0 .
An object or reference type in a language such as Java is also a record, which has as its first item a pointer or other code that indicates its class. In Java, reference types are capitalized, e.g. Integer.
As in this example, a record often contains other pointers. This is sometimes called a boxed integer .