Entity

An entity is something that exists. In its broadest sense, the concept is the most general category of being and encompasses anything that is identifiable, including living beings, inanimate objects, places, events, ideas, numbers, properties, and relations. It is controversial whether empty space and absences, such as holes or shadows, are also entities or should be regarded as nonentities. The words object, thing, and being are often treated as synonyms for entity, but they have distinct connotations and are not always interchangeable. Various fundamental types of entities have been proposed, but it is disputed whether they are all part of reality. Particulars are individual, nonrepeatable entities, such as a specific apple. They contrast with universals, which are general, repeatable entities, such as the color red. Concrete entities exist in space and time and causally interact, such as a cat, which is not the case for abstract entities, such as the number 7. Independent entities exist on their own, whereas dependent entities require or are grounded in other entities. Other suggested types include possible, actual, and necessary entities; observable and unobservable entities; and fictional and intentional entities. Entities are typically treated as having an identity that distinguishes them from other entities, expressed in the principle "no entity without identity". Questions of identity are closely connected to composition and boundaries: some entities are composed of smaller entities, such as a table made up of a tabletop and legs, while boundaries separate entities from each other, marking where one thing ends, and another begins. The concept entity is relevant to many fields. Metaphysics and ontology study what an entity is, which entities exist, and how they may be divided into categories of being. Philosophy of language, philosophy of mind, and epistemology discuss how linguistic representations or mental processes refer to entities. Information science...