The concept of liminality was developed in Arnold Van Gennep's book "Rites of Passage," and later expanded upon by Victor Turner. It refers to a state of openness and ambiguity characteristic of the intermediate phase in a tripartite space-time structure (consisting of a preliminal or prior phase, a liminal or intermediate phase, and a postliminal or subsequent phase). Liminality is directly related to the idea of communitas, as it represents an anti-structure and anti-hierarchy phenomenon within society. In such a state, a generic "spiritual" communion among social subjects surpasses the specifics of stratification. Consequently, it is the moment where trivial distinctions are suspended, allowing "passage" between different social conditions. It represents being on a threshold, between something that has passed and something yet to come. Conditions such as illness, adolescence, the state between sleep and wakefulness, or temporary madness are considered liminal states, as are journeys, whether undertaken for pleasure or necessity. Liminality can also apply to places, such as airports or prisons, and to personal or group events Liminal spaces have inspired an Internet aesthetic that portrays empty or abandoned places that appear eerie, desolate, and often surreal. These spaces, related to the concept of liminality, can be transitional areas like hallways or rest areas, as well as places with nostalgic appeal, such as playgrounds and empty houses. Generally, images of liminal spaces depict abnormally empty and dreamlike places. Research from the Journal of Environmental Psychology suggests that liminal spaces may seem creepy or strange because they fall into an uncanny valley of architecture and physical locations.