ECS architecture is centered on a strict separation between the identity of a simulation entity, its data, and its interactions. It escapes the paradigmatic rigid inheritance patterns seen in Object Oriented Programming, where entities are defined as monolithic classes that bring the three aforementioned aspects under a unified, sometimes bloated, structure. In ECS, an 'entity' is not an instance of a concretely defined class or an explicitly defined data structure; it is, abstractly, a fluid composition of pieces of data as they are associated with a unique identifier representing the entity, each piece of data following some concretely defined structure that delineates some aspect of the entity state (constant or variable, and transient or permanent), like motion state and collision parameters.