The document defines key concepts of entity-relationship modeling including entities, attributes, relationships, and cardinality. Entities represent real-world objects, attributes provide distinguishing characteristics of entities, and relationships define associations between entities. Relationships can be one-to-one, one-to-many, or many-to-many, depending on whether an entity instance relates to only one, many or many instances in the related entity. Entity-relationship diagrams provide a graphical representation of data and relationships to support business activities and performance monitoring.