Orgasm is the conclusion of the plateau phase of the sexual response cycle, shared by both men and women. During orgasm, both men and women experience quick cycles of muscle contraction in the lower pelvic muscles, which surround both the anus and the primary sexual organs.

Orgasms in both men and women are often associated with other involuntary actions, including vocalizations and muscular spasms in other areas of the body. Also, a generally euphoric sensation is associated with orgasm.

Afterwards, orgasm generally causes perceived tiredness, and both men and women often feel a need to rest. This is recently attributed to the release of prolactin. Prolactin is a hormone typically present in neuroendocrine response in depressed mood and irritation. A recent study at the University of Groningen has indicated significant differences in brain activity during the female and male orgasm.PET (brain) scans showed that both the female and male orgasm 'shut down' areas in the brain associated with anxiety and fear (the amygdala). It was found that the male orgasm focused the brain on sensory input from the genitals more than a female orgasm.

During orgasm, a human male experiences rapid, rhythmic contractions of the anal sphincter, the prostate, and the muscles of the penis. These contractions typically force stored semen to be expelled through the penis's urethral opening. The process generally takes from three to ten seconds, and is usually considered highly pleasurable.

Orgasm is achieved after direct stimulation of the penis for a period of time. This stimulation can be caused by sexual intercourse, manual masturbation, fellatio, or a sensual vibrator. Any sexual stimulation of the penis may eventually result in ejaculation and orgasm.

As a man ages, it is normal for the amount of semen he ejaculates to diminish, and hence, the length of time the man sustains orgasm also diminishes somewhat. This does not normally affect the pleasurable feeling of orgasm, but merely shortens its duration.

Following ejaculation, a refractory period usually occurs during which a man cannot achieve another orgasm. This period can be anywhere from less than a minute to over several hours, depending on age and other individual factors.

As a man nears orgasm during stimulation of the penis, he feels an intense pulsating sensation of neuromuscular euphoria. These highly pleasurable rhythmic pulses begin with a throb of the anal sphincter and travel to the tip of the penis. The pulses eventually increase in both speed and in intensity as the orgasm approaches, building up to a final "plateau" of pleasure which is sustained for several seconds. This plateau is what is referred to as the actual orgasm. It is during this time that semen is ejaculated and may continue to be ejaculated for a few seconds after the euphoric sensation gradually tapers off. It is believed that the exact feeling of "orgasm" varies from one man to another, but all agree that it is highly pleasurable.

In a human female orgasm, orgasm is preceded by moistening of the vaginal walls, and an enlargement of the clitoris due to increased blood flow trapped in the clitoris's spongy tissue. Some women exhibit a sex flush, a reddening of the skin over much of the body due to increased blood flow to the skin. As a woman comes closer to having an orgasm, the clitoris moves inward under the clitoral hood, and the labia minora (inner lips) become darker. As orgasm becomes imminent, the outer third of the vagina tightens and narrows, while overall the vagina lengthens and dilates and also becomes congested from engorged soft tissue. The uterus then experiences muscular contractions. A woman experiences full orgasm when her uterus, vagina, anus, and pelvic muscles undergo a series of rhythmic contractions. The majority of women consider these contractions to be very pleasurable, although not all sexually active women experience this.

After the orgasm is over, the clitoris re-emerges from under the clitoral hood, and returns to its normal size in less than 10 minutes.

In a disputed study, female orgasm has been linked to education and income, with heterosexual women with post-secondary degrees more likely to reach orgasm than their less-educated counterparts. ^[12]

The study methodology has been quite disputed. It is based on a computer assisted phone survey of 19,307 Australians. In fact, the abstract of the research states: "Demographic and sexual history variables were comparatively weakly associated with orgasm." Linking demographics to orgasms was not the aim of the research. The actual study barely references the linkage between demographics and orgasm.

Unlike men, women either do not have a refractory period or have a very short one and thus can experience a second orgasm soon after the first; some women can even follow this with additional consecutive orgasms. This is known as having multiple orgasms. After the initial orgasm, subsequent climaxes may be stronger or more pleasurable as the stimulation accumulates. Research shows that about 13% of women experience multiple orgasms; a larger number may be able to experience this with the proper stimulation (such as a vibrator) and frame of mind. However, for some women, their clitoris and nipples are very sensitive after climax, making additional stimulation initially painful. Taking deep, rapid breaths while continuing stimulation can assist in releasing this tension.