sentences:  Some forms of non-penetrative sex, particularly when termed "outercourse," include penetrative aspects, such as penetration that may result from forms of fingering or oral sex.People engage in non-penetrative sex for a variety of reasons, including as a form of foreplay or as a primary or preferred sexual act.Heterosexual couples may engage in non-penetrative sex as an alternative to penile-vaginal penetration, to preserve virginity, or as a type of birth control.