Reality, in everyay usage, means "the state of things as they actually exist". The term reality, in its widest sense, includes everything that is, whether or not it is observable or comprehensible. Reality in this sense may include both being and nothingness, whereas existence is often restricted to being (compare with nature). In other words, "reality", as a philosophical category includes the formal concept of "nothingness" and articulations and combinations of it with other concepts (those possessing extension in physical objects or processes for example).