A data dictionary is:

• A. A glossary of business terms
• B. A data dictionary contains a list of all files, the number of records in each file, and the names and types of each field; most DBMS keep the dictionary hidden from users
• C. A software library of functions
• D. A data model for cloud computing

Answer: (B)

A data dictionary is a metadata repository that describes data structures in a database system. It records what data exists, where it’s stored, and how it’s defined. Typically, it lists all files (tables), the number of records in each table, and the names and types of each field, along with constraints and other attributes. In most DBMS, this metadata is maintained in a system catalog or data dictionary and is kept hidden from regular users to protect integrity and allow the system to manage data efficiently. This is different from a glossary of business terms (which defines business concepts), a software library (which is a set of functions), or a data model for cloud computing (which is a design framework).