ER Diagram: ER Diagrams are most often used to design or debug relational databases in the fields of software engineering, business information systems, education, and research. ER diagrams also are often used in conjunction with data flow diagrams (DFDs), which point out the flow of information for processes or systems.

Schema: The term "schema" means the organization of data as a blueprint of how the database is constructed (divided into database tables in the case of relational databases). The formal definition of a database schema is a set of formulas (sentences) called integrity constraints imposed on a database.