Data modeling diagrams

software system design modeling tool

An entity is something that exists as itself. It does not need to be of material existence. In particular, abstractions and legal fictions are usually regarded as entities. In general, there is also no presumption that an entity is animate, or present. The verb tense of this form is to 'entitize' - meaning to convert into an entity; to perceive as tangible or alive.

describes inter-related things of interest in a specific domain of knowledge;composed of entity types (which classify the things of interest) and specifies relationships that can exist between instances of those entity types

thumb|320px|Example of an IDEF1X diagram.

visual representation of a certain kind of data model that contains entities, their relationships, and the constraints that are placed on them