““Entities that store one value are called simple entities. Compound entities are groups of related simple entities, so a compound entity can contain more than one value. For example, a unit in a strategy game normally includes many simple entities that describe its health, damage capability, maximum speed, and so on. Collectively, these make up a compound entity, and the simple entities that make it up are known as its attributes. Thus, a unit’s health is an attribute of the unit.””