Communitas is a Latin noun commonly referring either to an unstructured community in which people are equal, or to the very spirit of community. It also has special significance as a loanword in cultural anthropology and the social sciences. Victor Turner, who defined the anthropological usage of communitas, was interested in the interplay between what he called social 'structure' and 'antistructure'; Liminality and Communitas are both components of antistructure.

Communitas refers to an unstructured state in which all members of a community are equal allowing them to share a common experience, usually through a rite of passage. Communitas is characteristic of people experiencing liminality together. This term is used to distinguish the modality of social relationship from an area of common living. There is more than one distinction between structure and communitas. The most familiar is the difference of secular and sacred. Every social position has something sacred about it. This sacred component is acquired during rites of passages, through the changing of positions. Part of this sacredness is achieved through the transient humility learned in these phases, this allows people to reach a higher position.

Communitas is an acute point of community.^{[further explanation needed]} It takes community to the next level and allows the whole of the community to share a common experience, usually through a rite of passage. This brings everyone onto an equal level: even if you are higher in position, you have been lower and you know what that is.

Turner (1969, Pg.132; see also ) distinguishes between:

Communitas as a concept used by Victor Turner in his study of ritual has been criticized by anthropologists such as John Eade and Michael J. Sallnow's book Contesting the Sacred (1991).

At the heart of Turner’s theory is the notion that communitas involves a connection to the sacred, elicits powerful emotional experiences, and plays a key role in revitalizing social bonds and energies. In this sense, Turner’s work is closely linked to Durkheim’s The Elementary Forms of Religious Life. Although Turner does not directly reference Durkheim’s seminal work in The Ritual Process, it is clear that Durkheim's ideas on collective effervescence form a fundamental part of Turner’s argument. For instance, Turner states:

“Spontaneous communitas is richly charged with affects, mainly pleasurable ones. Life in "structure" is filled with objective difficulties... Spontaneous communitas has something magical about it. Subjectively there is in it the feeling of endless power... Structural action swiftly becomes arid and mechanical if those involved in it are not periodically immersed in the regenerative abyss of communitas.”

Edith Turner, Victor's widow and anthropologist in her own right, published in 2011 a definitive overview of the anthropology of communitas, outlining the concept in relation to the natural history of joy, including the nature of human experience and its narration, festivals, music and sports, work, disaster, the sacred, revolution and nonviolence, nature and spirit, and ritual and rites of passage.