Data Dictionary is a centralized repository of information about data such as meaning, relationships
to other data, origin, usage, and format. The term may have one of several closely related meanings pertaining to databases and database management systems (DBMS). Data dictionary helps define the details of a data stored in a field. Database users and application developers can benefit from an authoritative data dictionary document that catalogs the organization, contents, and conventions of one or more databases. This typically includes the names and descriptions of various tables and fields in each database, plus additional details, like the type and length of each data element. There is no universal standard as to the level of detail in such a document.