Liminality is a term used to identify a person or place that is considered in-between, or in a state of transition. The Latin root, līmen, is considered to mean "a threshold," or a point between two possible states in a process or of existence. In some cases, the term liminal is used as an adjective for describing this state.
Originally, the idea for liminality came about from the studies and publication of the French folklorist, Arnold van Gennep. In 1909, he published a work known as Rites de Passage, where he coined the term. Later, a British anthropologist by the name of Victor Turner further developed the idea in his book, The Forest of Symbols.
The first understanding of liminality by these authors revolved around cultural rituals, which can be broken down into a three-phase process. In the first phase, an individual was separated from what was known to him, such as a boy being sent out into the forest. Then the liminal phase begins, where the boy is on the threshold and he faces a transformation, which may involve a task such as completing a hunt alone in order to prove his manhood. Last is the re-entry into society, where he has traversed the liminality and come through to the other side to be accepted among his community again.
As a concept, liminality can be applied to understand many circumstances and studies including people, physics, or even metaphysics and vary from the small to quite large. With respect to time, for example, the concept can apply to numerous natural occurrences, such as the equinoxes and solstices that occur every year, or the transitions from night to day. Refugees, or other people with immigrant status, can be considered liminal, where during their transitional state they have no country to which they belong. Schrödinger's cat can be viewed as a liminal being, in that it is perceived of as maintaining an indefinite threshold state until it is observed and its condition is known.
There is a great deal of liminality in forms of storytelling as well as in numerous literary works and other media. Poets can be found using a good deal of liminal imagery to invoke emotional response with a flower bud, a moment of twilight and so forth. In fiction, liminality is used to create creatures and people that exist marginally, such as vampires, werewolves, or centaurs. Characters often fall into liminal plots where they come of age or transition from being single and lonely into finding love and marriage. Some stories also use liminal settings that form a sort of purgatory for a character where he awaits judgment or makes some discovery as to his condition.