Masturbation is when a person touches their own sex organs to have pleasure. It often results in an orgasm.

Masturbating may be done alone, but can also be done with another person. This is called "mutual masturbation". Vibrators and dildos can be used to make masturbation easier or feel better, but it is often done with just a person's hand. Studies have shown that many people masturbate regularly.

Animals can masturbate too.

Female masturbation 
The female sex organ most sensitive to touch is the clitoris. Therefore, female masturbation almost always involves stimulating the clitoris, either by hand or with a vibrator. Many women also enjoy the feeling of fingers or a sex toy in the vagina, but this is a secondary sensation that is not necessary for orgasm, and that rarely results in orgasm on its own. Some women find stimulation of the front vaginal wall particularly pleasurable. The anus is rich in nerve endings and is also sometimes stimulated during masturbation, as are the nipples.

Masturbation is usually continued until orgasm. Some women may have problems reaching an orgasm, especially when they are young, and have little experience masturbating.

Some women experience "multiple orgasms" - several orgasms in a row without loss of arousal. It should be noted, however, that women who are not capable of multiple orgasms report as much orgasmic satisfaction as women who are multi-orgasmic.

Male masturbation 

Masturbation for males is the act of stimulating the penis manually to provide self-pleasure. For older teens and adults, masturbation usually ends in what is called an ejaculation (the release of liquid called semen which contains sperm cells). This ejaculation is usually accompanied by a powerful, pleasurable feeling called an orgasm. Most boys start masturbating between the age of 12 and 15.

There are many ways in which a male can choose to masturbate. The most common of these techniques is using the hand. A man simply wraps his hand or two or three fingers around the shaft of his penis (in erection) and moves his hand up and down. Sometimes a lubricant is used to create a softer sensation. As the sensation increases in intensity, the rate of hand movement generally quickens until orgasm occurs. Orgasm is a very pleasurable feeling which results in semen being ejaculated from the penis.
Men may also rub and touch other sensitive areas of the body such as the scrotum (the place where the testicles are located). Due to the placement of the prostate gland, another method (though much more of a social taboo) involves inserting an object, like one's hand or a sex toy, into the anus to rub against the prostate. This causes a sensation of pleasure through the male's body, and has been stated to cause orgasms more pleasurable than those caused by simply rubbing the shaft.

Masturbation frequency, age and sex 

If and how often people masturbate depends on many things. One of the things it depends on is hormone levels. Hormones cause sexual arousal. Other things that the frequency of masturbation depend on sexual habits. Sexual habits are sexual activities that people do because they are used to doing them. Other people of the same age or standing - called peers - can also influence this frequency. General health is another of the many factors. The general attitude towards masturbation is formed by culture. Medical causes have also been associated with masturbation.

"Forty-eight female college students were asked to complete a sexual attitudes questionnaire in which a frequency of masturbation scale was embedded. Twenty-four of the women (the experimental group) then individually viewed an explicit modeling film involving female masturbation. One month later, all subjects again completed the same questionnaire. Subjects in the experimental group also completed a questionnaire evaluating aspects of the film. Results indicated that the experimental group reported a significant increase in the average monthly frequency of masturbation, as compared to the control group. This same group, however, reported that the film had no effect on sexual attitudes or behavior."

A 2004 survey by Toronto magazine NOW was answered by an unspecified number of thousands. The results show that an overwhelming majority of the males — 81% — began masturbating between the ages of 12 and 15. Among females, the same figure was a more modest majority of 55%. (Note that surveys on sexual practices are prone to self-selection bias.) It is not uncommon, however, to begin much earlier, and this is more frequent among females: 18% had begun by the time they turned 12, and 6% already by the time they turned 10. Being the main outlet of child sexuality, masturbation has been observed in very young children. In the book Human Sexuality: Diversity in Contemporary America, by Strong, Devault and Sayad, the authors point out, "A baby boy may laugh in his crib while playing with his erect penis (although he does not ejaculate). Baby girls sometimes move their bodies rhythmically, almost violently, appearing to experience orgasm."

A 2004 magazine survey in Canada found that 43% started masturbating when they were about 12–13 years old. When boys start masturbating, wet dreams often stop since semen is taken out from his body regularly.
According to a Canadian survey of Now magazine readers, (cited above), the frequency of masturbation declines after the age of 17. However, most males masturbate daily, or even more frequently, well into their 20s and sometimes far beyond. This decline is more drastic among females, and more gradual among males. While females aged 13–17 masturbated almost once a day on average (and almost as often as their male peers), adult women only masturbated 8–9 times a month, compared to the 18–22 among men. It is also apparent that masturbation frequency declines with age. Adolescent youths report being able to masturbate to ejaculation six or more times per day, though some men in older middle age report being hard pressed to ejaculate even once per day.  The survey does not give a full demographic breakdown of respondents, however, and the sexual history of respondents to this poll, who are readers of an urban Toronto lifestyle magazine, may not extend to the general population.

It appears that females are less likely to masturbate while in a heterosexual relationship than men. Both sexes occasionally engage in this activity, however, even when in sexually active relationships.  Popular belief asserts that individuals of either sex who are not in sexually active relationships tend to masturbate more frequently than those who are; however, much of the time this is not true as masturbation alone or with a partner is often a feature of a relationship.  Contrary to conventional wisdom, several studies actually reveal a positive correlation between the frequency of masturbation and the frequency of intercourse as well as the number of sex partners. One study reported a significantly higher rate of masturbation in gay men and women who were in a relationship.

Cultural views and practices
The Catholic church says masturbation is a 'gravely disordered action'. Among men masturbation may be seen as a sign of weakness. There are slang terms for it that are used as insults.

The Sambia tribe of New Guinea has rites of passage surrounding manhood. They include  frequent ejaculation by fellatio. Semen is valued. Masturbation is seen as a waste of semen. Because of this, it is frowned upon but frequent ejaculation is encouraged. The capacity and need to ejaculate is nurtured for years. This is done from an early age through fellatio. This allows the semen to be consumed rather than wasted. Semen is ingested for strength. It is considered in the same line as mothers' milk.

Other cultures have rites of passage into manhood that end in the first ejaculation of a male. This is often by the hands of a tribal elder.  In some tribes such as the Agta in the Philippines, stimulation of the genitals is encouraged from an early age.  At puberty, the young male is then paired off with a "wise elder" or "witch doctor". This person uses masturbation to build his ability to ejaculate in preparation for a ceremony. The ceremony ends in a public ejaculation before a celebration. The ejaculate is saved in a wad of animal skin and worn later to help conceive children.  In this and other tribes, the measure of manhood is actually associated more with the amount of ejaculate  than penis size.  Frequent ejaculation through masturbation from an early age fosters frequent ejaculation well into adulthood.

Masturbation marathons have occurred in the U.S. and UK. These events provide a supportive environment where masturbation can be performed openly.

Function 
Masturbation may increase fertility during sexual intercourse. In females, it can regulate the conditions of the vagina, cervix and the uterus. This can either increase or decrease the chance of conception. Whether the chance is increased or decreased depends on the timing of the masturbation. This timing is a subconscious decision. If she has intercourse with more than one male, it favors the chances of one or the other male's sperm reaching her egg.

Female masturbation can also protect against cervical infections. It does this by increasing the acidity of the cervical mucus and by moving debris out of the cervix.

The function of masturbation in males is to flush out old sperm with low motility from the male's genital tract. The next ejaculate contains more fresh sperm, which has higher chances of achieving conception during intercourse. If more than one male is having intercourse with a female, the sperm with the highest motility will compete more effectively.

Health and psychological effects

Benefits 
The physical effect of masturbation and having an orgasm or ejaculating is heightened arousal while epinephrine courses through the body, producing dopamine also known as the happy chemical, shallow breath and post-climactic euphoria.

It is held in many mental health circles that masturbation can relieve depression, stress and lead to a higher sense of self-worth.  Masturbation can also be particularly useful in relationships where one partner wants more sex than the other — in which case masturbation provides a balancing effect and thus a more harmonious relationship.

Mutual masturbation, the act by which two or more partners stimulate themselves in the presence of each other, allows a couple to reveal the map to their pleasure centers. Witnessing a partner masturbate is an educational activity to find out the method a partner uses to please them self, allowing each partner to learn exactly how the other enjoys being touched.

In 2003, an Australian research team led by Graham Giles of The Cancer Council Australia concluded that frequent masturbation by males appears to help prevent the development of prostate cancer.

A study published in 1997 found an inverse association between death from coronary heart disease and frequency of orgasm even given the risk that myocardial ischaemia and myocardial infarction can be triggered by sexual activity. Excerpt: "The association between frequency or orgasm and all cause mortality was also examined using the midpoint of each response category recoded as number of orgasms per year.  The age adjusted odds ratio for an increase of 100 orgasms per year was 0.64 (0.44 to 0.95)".  That is, a difference between any two subjects appeared when one subject ejaculated at around two or more times per week than the other.  Assuming a broad range average of between 3-5 ejaculations per week for a healthy males, this would mean 5-7 ejaculations per week. This is consistent with an article on the benefits against prostate cancer  However, the article notes that "The question of causation is complex... several explanations are possible".

Masturbation is also seen as a sexual technique that protects individuals from the risk of contracting sexually transmitted diseases. Support for such a view, and for making it part of the American sex education curriculum, led to the dismissal of US Surgeon General Joycelyn Elders during the Clinton administration.  A 2011 study from the Indiana University supports the assertion.  After taking age and partner status into account, the study showed that sexually active boys who masturbated regularly were eight times more likely to have used a condom during their last intercourse than other boys.  This positive outcome has been observed in other studies and has been the basis of public health policy in Great Britain promoting masturbation.

Some people actually consider masturbation as a cardiovascular workout. Masturbation makes most people feel good and can sometimes replace sexual intercourse when one cannot find a partner. It can also prepare one for sexual intercourse.

Blood pressure 
A small study has shown that a test group which only had intercourse experienced, as a whole, lower blood pressure in stressful situations than those who had intercourse but also had masturbated for one or more days.

Insertion 
Objects inserted into the vagina or anus should be clean and should not be able to scratch or break. Care should be taken not to fully insert anything into the anus — any object used should have a flared or flanged base; otherwise, medical help may be needed to get it out. Modern dildos and anal plugs are designed with this feature.

Pregnancy 
Masturbation involving both a man and a woman (see mutual masturbation) can result in pregnancy only if semen contacts the vulva. Masturbation with a partner can also theoretically result in transmission of sexually transmitted diseases by contact with bodily fluids.

Problems for males 
A man whose penis has suffered a blunt trauma or injury during intercourse may rarely sustain a penile fracture or suffer from Peyronie's disease. Phimosis is "a contracted foreskin (that) may cause trouble by hurting when an attempt is made to pull the foreskin back". In these cases, any energetic manipulation of the penis can be problematic.

Lawrence I. Sank observed that masturbating prone (lying face downward) could be responsible for sexual problems in some men, including anorgasmia and erectile dysfunction, as observed in four men he examined. He coined the term traumatic masturbatory syndrome to describe this theory. As of 2007, no follow-up research has been conducted and the idea is not familiar or widely-held within the medical community.  Some sources, however, give credence to the idea. One sex therapist condemned masturbation by rubbing against a pillow or mattress and Lipsith et al. suggest that masturbation could play a part in male psychogenic sexual dysfunction (MPSD), citing Sank as their authority. MPSD is a difficulty in reaching orgasm during intercourse, and developing a dependence on masturbation.

Compulsive masturbation 
Masturbating frequently presents no physical, mental or emotional risk in itself, but masturbation can be used to relieve boredom or stress. In either case, as with any "nervous habit", it is more helpful to consider the causes of the boredom or of the stress, rather than try to repress the behavior itself, in this case masturbation.

There is some discussion between professionals and other interested parties as to the existence or validity of sexual addictions. Nevertheless, there are lists of warning signs such as when sexual activity affects a person's ability to function in everyday life, or is placing them at risk, for example, of pursuing illegal or destructive activities.  Very frequent and compulsive masturbation may be seen as a sign of sexual addiction.

Philosophical views
Immanuel Kant considered masturbation a violation of one's duty to one's self and an unnatural act, stating it was against natural law. Sigmund Freud regarded masturbation as unhealthy. Margaret Sanger frequently stated that masturbation was unwise.

Masturbation in non-human animals 
Not only humans masturbate, animals do too. The following animals have been seen masturbating: dogs, several kinds of monkeys and apes, cows,> horses, whales, bats, and sheep. Even birds and reptiles masturbate (turtles, for example). In this case, this does not only affect animals that were domesticated, and live in captivity, but also includes wild animals, of both sexes. 

Bears have been documented to masturbate, while they watch other bears mating. 

Techniques used vary: Manual stimulation using hands, paws, feet, or tail is common, but autofellatio also occurs: Animals , rub their penis against the belly, or against other objects. Some species have been known to make tools that help them masturbate. Some species have shown to ejaculate spontaneously, without being stimulated first. Certain species are known to also stimulate other erogenous zones, such as the nipples, or the antlers in deer. Female mammals often masturbate by stimulating the clitoris, which is present in all mammal species.

References

Other websites 
 The Basics | JackinWorld

Human sexuality