The concept of liminality was first theorized by an Arnold van Gennep. In his book, The Rites of Passage, Gennep discusses the schema of the rite of passage as it proceeds from preliminal rites (rites of separation), to liminal rites (rites of transition), to postliminal rites (rites of incorporation).
By theorizing rites of passage, Gennep posits that transitional moments can be observed universally. Then, Victor W. Turner developed van Gennep's theory conceptually by applying the idea of liminality to a variety of contexts and understand the different human conditions and activities in societies of larger scale.
Turner articulates the notion of liminality thus:
The attributes of liminality or of liminal personate ('thresh-old people') are necessarily ambiguous, since this condition and these persons elude or slip through the network of classifications that normally locate there; they are betwixt and between the positions assigned and arrayed by law, custom, convention, and ceremonial.
Anthropologists, sociologists, historians, social scientists, and other scholars in the humanities are still inspired by Turner and have utilized the concept of liminality in their studies.