An Entity Relationship Diagram, ERD, is a flowchart that demonstrates how entities (i.e: people, concepts, or objects) relate to one another within a system. ERDs may be used to model relationship data bases, in terms of business rules. ERDs are oftentimes the first initial step in determining the requirements of an information systems project. They are used to analyze existing databases, in order to resolves issues. By creating an ERD, the diagram is able to determine where an issue is occurring. ERD help in analyzing databases and modeling new data bases.
ERDs are made up of entities, relationships, and attributes. Entities may be a person, object, event, or concept– nouns, relationships are how entities are associated with one another, and attributes are characteristics of the entities.
I like that you used a hospital ERD as on example. It really broadened my understanding of ERDs