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An entity represents a real-world object or concept with a unique existence in the database. It is depicted as a rectangle in ER diagrams.

An attribute is a property or characteristic of an entity or relationship. Each attribute has a domain of values it can take.

A relationship describes an association among two or more entities, usually represented by a diamond shape.

A primary key is an attribute or a set of attributes that uniquely identifies an entity instance in an entity set.

A composite key is formed by combining two or more attributes to uniquely identify an entity instance when a single attribute is not sufficient.

A weak entity cannot be uniquely identified by its own attributes alone and relies on a 'part-of' relationship with another entity.

Participating entities refer to the distinct entities that are involved in a relationship.

Cardinality defines the number of instances of one entity that can or must be associated with each instance of another entity.

This specifies whether all instances of an entity are required to participate in a relationship (total participation) or not (partial participation).

An Entity-Relationship diagram is a visual representation of entities, attributes, and relationships between them in a database.

An identifier is any attribute or combination of attributes that uniquely identifies an entity instance within an entity set.

A multivalued attribute can have multiple values for a single entity instance. They are typically depicted by a double oval in ER diagrams.

A derived attribute is not stored in the database but can be calculated or derived from other stored attributes.

A composite attribute is an attribute that can be divided into smaller sub-parts, which represent more basic attributes with independent meanings.