Swinging is usually defined as choosing a partner who is not your mate to engage in social, recreational sex for the mutual satisfaction of all involved.
Within the definitions given above there are several variations of swinging activity, but in every case swinging is a couples recreation.
Swingers may engage in:
Twosome - one male and one female engaged in sexual activity.
Threesome - a couple and a third party (extra male or extra female) mutually engaged in sexual activity.
Open Swinging - two couples (two men and two women) engaging in sexual activity in the same room at the same time.
Closed Swinging - two couples (two men and two women) engaged in sexual activity in separate rooms on the same premises simultaneously. (One couple in bedroom A, one couple in bedroom B.)
Group Swinging - sex with multiple partners for the sheer pleasure of the experience.
Bisexual - adults capable of enjoying sexual activity with members of their own sex as well as members of the opposite sex - much more common in the Lifestyle between females.
In every case, the spouse or partner of the participants, if not mutually engaged in the activity, is most often on the premises. Do not confuse swinging with playing around or having an affair.
Swinging is an open relationship with others of the same lifestyle, and both parties always know what pleasure their mate is experiencing - nothing is hidden.