What are the main object types of ABAP dictionary? | SAP ABAP

Tables: Tables are defined in the ABAP Dictionary independently of the database. A table having the same structure is then created from this table definition in the underlying database.
Views: are logical views on more than one table. The structure of the view is defined in the ABAP Dictionary. A view on the database can then be created from this structure.
Types (elements, structures, table types): Types are created in ABAP programs. The structure of a type can be defined globally in ABAP programs. Changes to a type automatically take effect in all the programs using the type.