Metadata, Schema, and Catalog are very common names in database, so what are the meaning of them? 1: Metadata In short, metadata is the data about other data. Metadata is defined as the data providing information about one or more aspects of the data; it is used to summarize basic information about data which can make tracking and working with specific data easier. 2: Schema Schemas are analogous to directories at the operating system level, except that schemas cannot be nested. There are several reasons why one might want to use schemas: To allow many users to use one database without interfering with each other. To organize database objects into logical groups to make them more manageable. Third-party applications can be put into separate schemas so they do not collide with the names of other objects. 3: Catalog The system catalogs are the place where a relational database management system stores schema metadata, such as information about tables and columns, and internal bookkeeping...