Data types are templates for creating data objects. Data types can be defined independently in the ABAP program or in the ABAP Dictionary. As attributes of a data object, data types can also exist in a non-independent state. Data types do not use any memory space for work data, but may require memory for administration information.
A data object is an instance of a data type and occupies as much memory space as its type specifies. An ABAP program only works with data that is available as content of data objects. Data objects are either created implicitly as named data objects, or ex anonymous data objects using CREATEDATA.
Data objects can be declared by reference to a non-generic data type of the same ABAP program or from the ABAP Dictionary. In this case, the data type determines the complete technical attributes of the data object. A data object can also be constructed in the ABAP program without completely specified type definitions. The data type of a data object of this type is always complete, but does not exist independently, but rather as an attribute of the data object, and is called a bound data type.
The data types of all class attributes belong to the static class properties. A LIKE addition enables you to refer to the visible class attributes without a prior object creation using the class component selector or reference variables
See also Types and Objects