Sex is a variable and complex interaction between partners, which includes a number of non-verbal expressions before, during and after the sexual act itself. These non-verbal expressions often significantly influence the course of sexual activities and the experience of partners during them.
The initiation of sexual activity takes place non-verbally in about half of the cases, and the tactics differ depending on whether a romantic relationship is just being established or it takes place within a long-term relationship. For a long-term relationship, some form of intense physical contact or nudity are among the usual ways of initiating sex.
In the process of establishing a new relationship, sex can be preceded by seduction, a strategic sequence of behaviors that one partner deliberately performs to lead the couple to sex. After the initiation of sexual activity, couples engage in foreplay, which typically includes kissing, caressing or massage.
Some of these same behaviors are important for partners after sex, or they can replace sexual intercourse. Nonverbal cues also enhance sexual arousal, with men and women differing in how much a preferred object is key to their arousal and what positions they find more comfortable during sex.
Rhythmic synchronization of partners plays an important role in arousal, but blushing or vocalization during sex is also a manifestation and/or impulse to arousal. The facial expression of pleasure occurs during the peak phase of sexual experience and arousal.