Final answer:
E-R diagrams utilize symbols to represent entities as rectangles, attributes as ovals, and relationships as diamonds with cardinality markers to depict how multiple instances of one entity correlate with instances of another entity in a database.
Step-by-step explanation:
Entity-Relationship (E-R) diagrams are a critical aspect of database design and development. In these diagrams, entities represent objects or concepts, often corresponding to database tables, which contain specific information. Each entity is symbolized by a rectangle containing the entity's name. Attributes, which are the properties or characteristics of an entity, are depicted by ovals connected to their respective entity, indicating columns in a table. A key attribute that uniquely identifies an entity instance is often underlined.
Relationships, showing how entities are related to one another, are represented by diamond-shaped symbols. These symbols often contain verbs and are connected to the involved entities with lines. Cardinality, indicating the counts of instances that are possible in the relationship, is described by placing symbols like '1', 'N', or a range (e.g., '0..1') near the ends of the relationship lines. This dictates how many instances of one entity can be associated with instances of another entity.
For a more comprehensive understanding, Special symbols such as double rectangles, double diamonds, and dashed lines show concepts like weak entities, identifying relationships, and inheritance respectively. Using these elements of E-R diagrams effectively can deliver a thorough representation of the database structure.