What is an entity-relationship diagram (ERD)?

An Entity-Relationship Diagram (ERD) is a graphical representation of entities and their

relationships to each other within a database. It is used to visualize the structure of a

database and how tables (entities) relate to one another.

• Entities are represented as rectangles.
• Attributes are shown as ovals connected to their entities.
• Relationships are represented as diamonds, showing how entities interact.

ERDs help in the conceptual design phase of a database, outlining entities, relationships,

and keys before implementation.