Security refers to the protection of data against unauthorized access. Security mechanisms of a DBMS makes sure that only authorized users are given access to the data in the database. The level of access for each user and the operations that each user can perform on the data will be monitored and controlled by the DBMS depending on the access privileges of the users.

The DBMS provides languages for the definition and manipulation of data in the database. The data structures are created using the data definition and manipulation, the DBMS creates an environment where the users can do their jobs without worrying about the physical implementation.

The DBMS provides a mechanism for the management of permanent storage of the data. The internal schema defines how the data should be stored by the storage management mechanism and the storage manager interfaces with the operating system to access the physical storage. A storage manager is responsible for the implementation of database management systems. A storage manager supports block oriented access to disk files, buffering of blocks, splitting the logical files-files larger than the maximum size of physical files allowed by the operating system ق│ô over multiple volumes, maintaining order of the physical blocks in order to minimize seeks in ordered scans, fuzzy check pointing and fuzzy dumping to support on-line backups and recovery and much more.

Data Catalog or data Dictionary is a system database that contains description of the data in the database (metadata). It contains information about data, relationships, constraints and the entire Schema that organize these features into a unified database. The data catalog can be queried to get information about the structure of the database.