In a Database Management System (DBMS), entities represent real-world objects, concepts, or things that are of interest to an organization or system. Entities are the fundamental building blocks of a database and are typically represented as tables in a relational database. Here are some key points about entities in DBMS:

1. Definition: An entity is a unique, distinguishable object or concept with its own set of attributes (characteristics or properties). Each entity represents a distinct type of object or concept in the domain being modeled.

2. Entity-Attribute-Value: An entity is composed of attributes that describe its properties or characteristics. Attributes represent specific pieces of information about the entity. For example, in a "Student" entity, attributes can include StudentID, Name, Age, and Gender.

3. Entity Relationships: Entities are related to each other through relationships. Relationships define associations, dependencies, or connections between entities. For example, in a university database, a "Student" entity can be related to a "Course" entity through an enrollment relationship.

4. Entity Identification: Each entity in a database must have a unique identifier called a primary key. The primary key uniquely identifies each instance or occurrence of the entity. For example, in a "Student" entity, the StudentID attribute can be designated as the primary key.

5. Entity Instances: An entity instance is a specific occurrence or occurrence of an entity. Each entity can have multiple instances, representing different real-world objects or concepts. For example, each student in a university database is an instance of the "Student" entity.

6. Entity Types: Entity types are the categories or classes to which entities belong. They define a set of entities that share common attributes, relationships, and behavior. For example, "Student," "Course," and "Faculty" are entity types in a university database.

7. Entity Integrity: Entity integrity refers to the concept that each entity instance must have a valid value for its primary key attribute. It ensures that no duplicate or null values exist for the primary key, maintaining the uniqueness and integrity of the entity.

Entities play a crucial role in conceptualizing and representing the real-world domain in a database. They capture the objects, concepts, or things of interest and provide the foundation for creating database tables, defining attributes, establishing relationships, and managing data within the DBMS.

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