Entity

An entity is a distinct object, person, place, concept, event, or thing about which information is stored in a database. In database design, entities represent the main objects of interest and serve as the foundation of data modeling. Each entity is described by a set of attributes that define its characteristics, such as name, ID, type, or other relevant properties. For example, in a student database, Student, Course, and Instructor are entities with attributes like Student ID, Course Name, and Instructor Email. Each individual occurrence of an entity is called an entity instance, which is uniquely identified by one or more key attributes. Similar entities are grouped into entity sets, where all instances share the same structure and attributes. Entities are linked through relationships that represent real-world interactions, allowing databases to organize and manage information efficiently. Properly defining entities, attributes, and relationships improves data consistency, reduces redundancy, supports efficient storage and retrieval, and provides the foundation for relational databases, Geographic Information Systems (GIS), and other information management systems.