Proxemics is one of several subcategories of the study of nonverbal communication. Other prominent subcategories include haptics (touch), kinesics (body movement), vocalics (paralanguage), and chronemics (structure of time). Proxemics can be defined as ""the interrelated observations and theories of man's use of space as a specialized elaboration of culture"". Edward T. Hall, the cultural anthropologist who coined the term in 1963, emphasized the impact of proxemic behavior (the use of space) on interpersonal communication. Hall believed that the value in studying proxemics comes from its applicability in evaluating not only the way people interact with others in daily life, but also ""the organization of space in [their] houses and buildings, and ultimately the layout of [their] towns"".In animals, Swiss zoologist Heini Hediger (1908-1992) had distinguished between flight distance (run boundary), critical distance (attack boundary), personal distance (distance separating members of non-contact species, as a pair of swans), and social distance (intraspecies communication distance). Hall reasoned that, with very few exceptions, flight distance and critical distance have been eliminated in human reactions, and thus interviewed hundreds of people to determine modified criteria for human interactions.In his work on proxemics, Hall separated his theory into two overarching categories: personal space and territory. Personal space describes the immediate space surrounding a person, while territory refers to the area which a person may ""lay claim to"" and defend against others. His theory on territoriality has been applied to animal behaviors as well; defending territory is regardedTemplate:By whom? as a means of ""propagation of the species by regulating density"".