An orgasm (sexual climax) is the conclusion of the plateau phase of sexual response cycle, and may be experienced by both males and females. Orgasm is characterized by intense physical pleasure, controlled by the involuntary, or autonomic, nervous system. It is accompanied by quick cycles of muscle contraction in the lower pelvic muscles, which surround the primary sexual organs and the anus. Orgasms are often associated with other involuntary actions, including muscular spasms in other areas of the body, a general euphoric sensation and, frequently, vocalizations.

The moments after orgasm are often a relaxing experience, which is attributed to the release of prolactin. Male and female brains demonstrate similar changes during orgasm, with brain scans showing a temporary reduction in the activity of large parts of the cerebral cortex.

Achieving orgasm

In men, the most common way of achieving orgasm is by the stimulation of the penis; while in women it is the stimulation of the clitoris. Such stimulation can be achieved from a variety of activities. In men, sufficient stimulation can be achieved during vaginal or anal sexual intercourse, oral sex (fellatio), or by masturbation. This is usually accompanied by ejaculation. In women, orgasm may be achieved during vaginal sexual intercourse, oral sex (cunnilingus), masturbation, or other non-penetrative sex, and may be by the use of a sensual vibrator or an erotic electrostimulation, besides other activities. Orgasm may also be achieved by stimulation of the nipples, uterus, or other erogenous zones. In addition to physical stimulation, orgasm can be achieved from psychological arousal alone, such as during dreaming (which may be a nocturnal emission).

Important in sexual stimulation are internal glands, called the Skene's glands in women and the prostate in men, two homologous structures. In common use, the term G-spot refers to these areas.

The stimulation can come from receptive intercourse, fingering, fisting, or penetration with a dildo or other sex toy.

Female orgasm

Discussions of female orgasm are complicated by the fact that, perhaps artificially, orgasm in women has sometimes been labelled as two different things: the clitoral orgasm and the vaginal orgasm.

The concept of vaginal orgasm as a separate phenomenon was first postulated

In 1966, Masters and Johnson published pivotal research about the phases of sexual stimulation. Their work included women and men, and unlike Alfred Kinsey earlier (in 1948 and 1953), tried to determine the physiological stages before and after orgasm. Masters and Johnson observed that both clitoral and vaginal orgasms had the same stages of physical response. They argued that clitoral stimulation is in fact the primary source of both kinds of orgasms.

Recent discoveries about the size of the clitoris show that clitoral tissue extends some considerable distance inside the body, around the vagina. This discovery may possibly invalidate any attempt to claim that clitoral orgasm and vaginal orgasm are two different things.