Entity-relationship model
This entity-relationship diagram (ERD) sample shows an entity-relationship model for a school. It was designed on the base of the Wikimedia Commons file: Entity-Relationship-Modell.svg. [commons.wikimedia.org/wiki/File:Entity-Relationship-Modell.svg]
"An entity–relationship model (ER model) describes inter-related things of interest in a specific domain of knowledge. An ER model is composed of entity types (which classify the things of interest) and specifies relationships that can exist between instances of those entity types.
In software engineering an ER model is commonly formed to represent things that a business needs to remember in order to perform business processes. Consequently, the ER model becomes an abstract data model that defines a data or information structure that can be implemented in a database, typically a relational database." [Entity–relationship model. Wikipedia]
The Chen's notation ER-diagram example "Entity-relationship model" was created using ConceptDraw PRO software extended with the Chen Notation solution from the Software Development area of ConceptDraw Solution Park.