Explain entity-relationship (ER) diagrams.

What will be an ideal response?

Entity-relationship (ER) diagrams use basic graphical symbols to show an organization of and relationships between data. In other words, ER diagrams show data items in tables (entities) and the ways they are related. ER diagrams help ensure that the relationships among the data entities in a database are correctly structured so that any application programs developed are consistent with business operations and user needs. In addition, ER diagrams can serve as reference documents after a database is in use. If changes are made to the database, ER diagrams help design them.