The definition of “existence” is a philosophical and ontological question that pertains to the nature of being and reality. Existence is a concept that encompasses the state of being alive or being present in the world. Philosophers have explored different aspects of existence, such as the distinction between existence and essence, the existence of abstract entities, and the nature of contingent and necessary existence. In ontology, the branch of philosophy concerned with the study of existence, questions about the existence of objects, properties, and abstract entities are central. For example, the question of whether mathematical objects like numbers and geometric shapes exist independently of human thought and language is a topic of debate in the philosophy of mathematics. Existentialist philosophy, as exemplified by Jean-Paul Sartre’s famous phrase “existence precedes essence,” emphasizes the idea that existence is prior to any predetermined essence or meaning. In metaphysics, the study of the fundamental nature of reality, questions about the existence of universals (general properties that multiple objects can share) and particulars (individual instances of those properties) are explored. The definition of existence is closely tied to broader questions about reality, identity, and the nature of being. Different philosophical traditions and schools of thought offer diverse perspectives on what it means to exist and the criteria for establishing the existence of entities or phenomena.