alexwileden:

Triad - Usually consists of a primary couple who are both in relationship with the same third party.  *Greg and Sara are married, and both are romantically tied to Tiffany.*

The W - Usually involves one “center” person who is romantically linked to two partners.  The Center’s partners may also be involved in other relationships.  *Greg is married to Sara, but is also in a relationship with Tiffany.  Sara does not have a relationship with Tiffany.  Both Sara and Tiffany may have relationships aside from Greg.*

Quad - This version occurs most often with two couples sharing relationships together.  *Greg and Sara are married.  Tiffany and Jim are married.  All four people (or any variation of the group) share relationships with one another*  The quad can be an open relationship (meaning that members are also allowed to pursue relationships outside the quad), but are often non-open (meaning it is only permissible for the 4 to have sexual relationships with one another).  The first scenario is similar in nature to swingers, while the second is not.

Polyfidelity - Started by the Kerista Village commune in San Fransisco, this version involves a group of people who consider all members as “primary partners”.  All members are in relationship with one another, but do not look outside the group for relationships.  (A non-open quad could be considered a small polyfidelity group.)

Mono/Poly - Sometimes in relationships, one partner identifies as polyamorous while the other does not.  In this case, the couple may choose a mono/poly relationship where one is involved in relationships outside the marriage while the other stays monogamous.  In most cases, the couple chooses to maintain their relationship as the only emotionally committed one, while the polyamorous partner is involved sexually with other partners.

Continue reading on Examiner.com Polyamory: A progressive approach to relationships - Milwaukee LGBT Community | Examiner.com http://www.examiner.com/lgbt-community-in-milwaukee/polyamory-a-progressive-approach-to-relationships#ixzz1fsrNRlPZ

I just find this really interesting.