Polyamory has its own unique multipartner terminology and language. One of the most popular styles of Polyamory is Polyfidelity. Sometimes also called closed group marriage. In Polyfidelity, groups of three or more partners consider themselves essentially married to each other. They usually live together in a single home and share their lives and resources such as married couples do. There may be any combination of males, females and sexual orientations. Polygyny, as it was practiced by the Mormons, is just one example of Polyfidelity. Classically, Polyfidelitous groups are sexually exclusive and do not engage in sexual relations outside the group. However, there are some group marriages which are "open," and which do allow for outside eromances. In the open marriage style relationships in which the members who consider themselves committed life partners nonetheless permit outside, sexual, romantic and loving relationships outside the marriage in a way that is agreed upon by the marital partners.
Some, but by no means all, "intentional communities" follow Polyamorous principles. The residents of the community may think of themselves as all "married" to each other (like the Oneida community in nineteenth century New York State) or not, but all members of the community may be viewed as legitimately available to each other as sexual and/or romantic partners (like the ZEGG community in present-day Germany or Windward in Washington state). Others have found Polyamory through residing in group homes and through coopertive housing living arrangements.
Finally at the less structured end of the spectrum are Intimate Networks. They are informal webs of people with varying levels of interpersonal bonding and commitment who share a belief in open multilateral relationships. Intimate Networks often develop around or among open marriages or open couples. People in Intimate Networks and other Polyamorous relationships sometimes refer to the depth of their relationships as "Primary," "Secondary," and "Tertiary" to describe the varying levels of commitment involved.
Primary Relationships are the closest relationship type, the person(s) given the most time, energy and priority in a person's life; includes high level of intimacy, attraction and commitment as demonstrated by marriage-level bonding (such as shared life paths, goals, parenting, economics, housing, important values, ongoing emotional support, etc.) Typically includes a desire for a shared lifelong future together.
Secondary Relationships are close relationship types, by definition they are given less in terms of time, energy and priority in a person's life than any primary relationship. Includes aspects of primary relating, such as sexuality and emotional support but usually involves fewer ongoing commitments as evidenced by fewer shared values, plans or financial/legal involvements. May include a desire for a long term future together.
Tertiary Relationships are relationships which may include emotional support or sexuality on a one-time or highly erratic schedule. Attention or energy is given in bursts but the relationship(s) is not a consistent part of one's life.