Swinging or partner swapping (sometimes referred to as the swinging lifestyle or simply the lifestyle) is a non-monogamous behavior, in which partners in a committed relationship agree, as a couple, for both partners to engage in sexual activities with other people, sometimes referred to as recreational or social sex. Swinging can take place in a number of contexts, ranging from a spontaneous sexual activity at an informal social gathering of friends to a swingers' club and can involve internet-based introduction services. The phenomenon of swinging (or at least its wider discussion and practice) is regarded by some as arising from the upsurge in sexual activity during the sexual revolution of the 1960s, made possible by the invention of the contraceptive pill and the prevalence of safer sex practices during the same period.