The ABAP Dictionary is part of the ABAP Workbench. In the ABAP Dictionary the developer can create, modify and view the following objects:
Database Tables and Views
Global Data Types
Type Groups
Domains
Matchcodes
Lock Objects
The main advantages of the ABAP Dictionary are: data integrity enforcement, manage data definitions with no redundancy and that it is perfectly integrated with the ABAP Workbench.
Ensuring that the data entered into the system is logical, consistent and complete is called Data Integrity. Using the ABAP Dictionary Data Integrity Rules can be deifined so that the system checks if the data that is entered is valid. An example of data integrity is to reject the date 02/30/2007 (because it doesn't exist).
When using the ABAP Dictionary, redundancy does not exist because the objects are created only once, and can be accessed in the entire system. It is important to note that this also helps to the consistency of information - there is only one definition possible for each object in the ABAP Dictionary.
When developing, the ABAP Workbench automatically recognizes the names and characteristics of the ABAP Dictionary.