what is an erd

An Entity-Relationship Diagram (ERD) is a type of flowchart that illustrates how "entities" such as people, objects, or concepts relate to each other within a system. ERDs are most often used to design or debug relational databases in the fields of software engineering, business information systems, education, and research. ERDs are composed of entity types (which classify the things of interest) and specify relationships that can exist between entities (instances of those entity types). ERDs are usually drawn in a graphical form as boxes (entities) that are connected by lines (relationships) which express the associations and dependencies between entities. ERDs are related to data structure diagrams (DSDs), which focus on the relationships of elements within entities instead of relationships between entities themselves. ERDs can also be used in conjunction with data flow diagrams (DFDs), which map out the flow of information for processes or systems.