Closed-group swinging is a a form of swinging that involves participants having multiple sexual partners who are all within a specific group of people. A common example of closed-group swinging is when couples who are friends regularly switch partners.
More About Closed-Group Swinging
Closed-group swinging relationships have some similarities to polyfidelitous relationships with an agreement to share multiple partners within the closed group. The main difference being the focus of the relationship. In this case, the focus is sexual rather than romantic.