Covens (House/Household/Clans) are groups of individual vampires or vampyre lifestylers, usually but not always located within a certain geographic area, who have banded together under a specific theme, set of ideals, traditions, common Sigil, havens, membership requirements, hierarchy and/or rites.
Covens range in size from as few as three members to as many as hundreds. Depending on their background, size and geographic location, Covens are referred to as Clutches and Circles for smaller groups; and Legacies, Households and Clans for larger groups.
Some Covens have "Subcovens", which represent a branch of the family tree.
Some titles given to leaders of Covens include Elder, High Priest, Patriarch, Matriarch, or Coven Master. There are no requirements for forming a Coven other than a group of people getting together, choosing a sigil, name and theme.
The organization and purpose of each Coven varies from fraternal (House Sahjaza); religious (Church of the Vampire -- not to be confused with the Vampire Church); or familial (Clan of Lilith).
Currently, some of the more established Covens are: House Sabretooth, House Omallie, Mavenlore, Della Noir, Blackdove, House Kheperu and Trylesta, House Eclipse, House Sahjaza, House Quinotaur, and House Nekhbet. There are many others, as well.