Masturbation is the manual excitation of the sexual organs, most often to the point of orgasm. It can refer to excitation either by oneself or by another (see mutual masturbation), but most commonly it is restricted to such activities performed alone. It is part of a larger set of activities known as autoeroticism, which also includes the use of sex toys and non-genital stimulation. There are also masturbation machines used to simulate intercourse. Masturbation and sexual intercourse are the two most common sexual practices. Some people are only able to achieve orgasm by masturbation rather than sexual intercourse. In the animal kingdom, masturbation has been observed in the male of every species of mammal.
The word masturbation is believed by many to derive from a plural Greek word for penis (μεζεα-- mezea) and the Latin verb turbare, meaning to disturb. A competing etymology based on a Latin expression manus turbare meaning "to disturb with the hand" is regarded by most dictionaries as "an old conjecture". The esoteric and little-used synonym manustupration derives from a similar etymology, manus stuprare.
The word onanism is used as a synonym because it refers to the Biblical story (Genesis 38:7-9) in which a man called Onan "spilled his seed upon the ground" to avoid impregnating his dead brother's wife (see levirate marriage) and, because "the thing which he did displeased the Lord", Onan was killed. Although of course the story refers to the sexual contraception method of coitus interruptus, the word came to refer to masturbation because both masturbation and coitus interruptus are sexual acts that do not lead to impregnation. Many people who have never read the bible are surprised to find that the Onan story is not about masturbation and conclude erroneously that the word "onanism" is now out of date, but the word is still in use.
Masturbation among women
Masturbation techniques among women are numerous and more varied than among men. They are influenced by a number of factors and personal preferences.
A woman may stroke or rub the vulva, especially the clitoris with her middle or index fingers, or even index and second fingers. This is pleasurable for most women, especially when rubbing the breast and nipples at the same time. A woman may sometimes insert one or more fingers inside the vagina and repeatedly stroke the frontal wall of her vagina where the g-spot is located. A woman may also use masturbatory aids such as a vibrator, dildo or Ben Wa balls to stimulate the vagina and clitoris.
A woman may masturbate while in a bathtub, shower, or even hot tub by using warm running water to stimulate the clitoris.
Or she may straddle a pillow, stimulating the clitoris through the labia and clothing, similar to frotteurism.
Some women reach orgasm by crossing their legs tightly and clenching the muscles in their legs, which creates friction.
Anal stimulation is also preferred by some women because of the thousands of sensitive nerves located in the anus.
Women may use lubrication as part of their masturbation technique.
Masturbation is one of the easiest ways for a woman to reach orgasm.
Masturbation among men
Men as a group employ fewer masturbation techniques than women. These too are influenced by a number of factors and personal preferences. The most common method of masturbating among males is to hold the penis with a loose fist and move the hand up and down the shaft until orgasm is achieved. The gliding motion of the foreskin reduces friction, thereby facilitating masturbation in the absence of artificial lubricant. Some circumcised males directly massage the glans, generally with the aid of a lubricant, but this is usually too irritating for uncircumcised males.
Another method practiced by a small proportion of males is to lie face down on a comfortable surface such as a mattress and rub the penis against it until orgasm is achieved. However, some clinicians have noted this as a potentially harmful practice called traumatic masturbatory syndrome. For both circumcised and uncircumcised men, masturbation may result in pain, irritation, or abrasion if performed too roughly. This problem may be less prevalent for uncircumcised men. Some use an artificial vagina, or simulacrum, for masturbation. Many males fondle their testicles or other parts of their body while masturbating.
Ejaculation of semen is sometimes controlled by wearing a condom or less frequently by ejaculating into an artificial vagina, a sock, a tissue or the toilet. Most males ejaculate onto their bodies and then clean up with a cloth or tissue. A controversial ejaculation control technique is to put pressure on the perineum, a spot about half way between the scrotum and the anus, just before ejaculating. This can redirect semen into the bladder. However, the technique may cause long term damage due to the pressure put on the nerves and blood vessels in the perineum. Some people are also able to reach orgasm without ejaculating. Proponents of tantric sex say that this is a learnable skill that can allow the male to require a shorter refractory period before they are able to again achieve orgasm.
The prostate gland is one of the organs that contributes fluid to semen. As the prostate is touch sensitive, some men directly stimulate it using a well-lubricated dildo inserted through the anus into the rectum. Similarly, a partner may provide the masturbation by hand and/or mouth and tongue, or by inserting a well lubricated finger into the anus for direct stimulation of the prostate.
Men who can reach their penis with their tongue or lips sometimes perform autofellatio, in which the man licks or sucks his own penis. However, research shows only one man in a thousand can do this to orgasm.
Masturbation and circumcision
Historically, some have seen a connection between circumcision and masturbation frequency, which remains a debated topic. In a 1410-man survey in the United States in 1992, Laumann found that: "A total of 47% of circumcised men reported masturbating at least once a month vs 34% for their uncircumcised peers." However, a less scientific internet based 85 male participant survey from Australia found that 60% of uncircumcised males masturbate weekly as opposed to 40% of circumcised men. 
It may be necessary or more comfortable for circumcised men to use a personal lubricant while masturbating since they do not have a foreskin.
Methods common to both human genders
Ways of masturbating common to members of both sexes include pressing or rubbing the genital area against an object, such as a pillow, inserting fingers or an object into the anus (see anal masturbation), and stimulating the penis or vulva/clitoris with electric vibrators, which may also be inserted into the vagina or anus. Members of both sexes may also enjoy touching, rubbing, or pinching the nipples while masturbating. Both sexes sometimes use lubricating substances to improve the sensation available.
Reading or viewing pornography, or sexual fantasy, are common adjuncts to masturbation in adolescence and adulthood. Masturbation activities are often ritualized. Various fetishes and paraphilias can also play a part in the masturbation ritual; potentially harmful or fatal activities include autoerotic asphyxiation and self-bondage.
Masturbation frequency, age and gender
It is understood that most people begin masturbating when reaching adolescence. Many scholarly and clinical studies have been done on the matter, and many informal surveys have asked the question. 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 10 and 15. Among females, the same figure was a more modest majority of 55%. It is not uncommon however to begin much earlier, and this is more frequent among females: 18% had begun by the time they turned 10, and 6% already by the time they turned 6. 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."
According to the Canadian survey cited above, the frequency of masturbation declines after the age of 17. 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 the ability to masturbate declines with age. Adolescent youths report being able to masturbate to ejaculation six or more times per day, while men in middle age report being hard pressed to ejaculate even once per day, on a daily basis.
(It should be noted that the survey results do not include a demographic breakdown of the respondents, so it is uncertain how reliable these results are.) In part this is due to the fact that females are less likely to masturbate while in a sexual relationship than men. Both sexes occasionally engage in this activity, however, even when in sexually active relationships (or happily married). In general, individuals of either sex who are not in sexually active relationships tend to masturbate more frequently than those who are.
Health and psychological effects
It is being increasingly recognised in mental health circles that masturbation can relieve depression 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.
Both from the standpoint of avoiding unwanted pregnancy and that of avoiding sexually transmitted diseases, masturbation is the safest of sexual practices. There is no credible scientific or medical evidence that manual masturbation is damaging to either one's physical or mental health, with the exception of some cases of Peyronie's disease and traumatic rupture. In such instances, aggressive manipulation (e.g. inversion during adolescence, bending or twisting) of the penis and subsequent injury to the tunica albuginea or corpus cavernosum results in a localised fibromatosis, distorting the erectile appearance. Contrary to popular myth, masturbation does not make the palms hairy or cause blindness or genital shrinkage. Lending some basis to the origin of the myth, zinc is both required to transport vitamin A from the liver to the retina, see  and , and is excreted in relatively high amount in semen. Thus, it is not inconceivable that in zinc-deficient or vitamin A-deficient environments excessive masturbation could have caused night blindness.
The only side-effects recorded are that repeated masturbation may result in tiredness or soreness, which tend to make repeated masturbation self-limiting in any case, and that the volume of ejaculate is temporarily reduced in men after multiple ejaculations until normal seminal volume is regained in a day or so. Nevertheless, people from a socially conservative or religious background and other sensitive persons may experience attendant feelings of guilt during or after masturbation.
Solitary masturbation carries no risk of pregnancy or sexually transmitted diseases. Masturbation with a man and a woman can result in pregnancy only if semen contacts the vulva. Any masturbation with a partner can theoretically result in transmission of sexually transmitted disease by contact with semen or female sexual fluids, and such contact should be avoided with any partner whose disease-negative status you are not sure of. Objects inserted into the vagina or anus should be clean and of a kind that will not 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 retrieval can require a visit to the emergency room. Most modern dildos and anal plugs are designed with this feature.
In 1994, when the first woman appointed US Surgeon General, Dr. Joycelyn Elders, mentioned as an aside that masturbation ought to be mentioned in the school curriculum, she was forced to resign, although many believe this was the result of her long history of promoting controversial viewpoints and not solely to her public mention of masturbation.
On July 16, 2003, an Australian research team led by Graham Giles of The Cancer Council published a medical study  which concluded that frequent masturbation by males may help prevent the development of prostate cancer. The study also indicated that this would be more helpful than ejaculation through sexual intercourse because full sex can transmit diseases that can increase the risk of cancer instead. See, for example, Risk Factors in Cervical Cancer.
Masturbation in history and society
Prehistoric rock paintings from around the world may depict male masturbation, though these are entirely matters of interpretation. Most early people seem to have connected human sexuality with abundance in nature. A clay figurine of the 4th millennium BC from a temple site on the island of Malta, depicts a woman masturbating. However, in the ancient world depictions of male masturbation are far more common.
Male masturbation became an even more important image in ancient Egypt: when performed by a god it could be considered a creative or magical act. The ancient Greeks had a more natural attitude toward masturbation than the Egyptians did, regarding the act as a normal and healthy substitute for other forms of sexual pleasure. They considered masturbation a safety valve against destructive sexual frustration. The Greeks also dealt with female masturbation in both their art and writings.
Excerpt from United States patent number 745,264, filed on May 29, 1903 by Albert V. Todd . It describes a device designed to prevent masturbation by inflicting electric shocks upon the perpetrator, by ringing an alarm bell, and through spikes at the inner edge of the tube into which the penis is inserted. View the complete patent: Sexpatent01.png, Sexpatent02.png, Sexpatent03.png, Sexpatent04.png. Patents of this kind were filed from c. 1850 to c. 1920. 
Modern medicine as mentioned before, recognizes that there is no significant harm (short term or long term) caused by the practice of masturbation, and regards it as a normal practice. In past times, however, some medical professionals taught that all sorts of deleterious effects could occur as a result of masturbation. Since the 19th century, many "remedies" have been devised for masturbation, including regularly eating corn flakes, physical restraint, electric shock, treating the genitalia with stinging nettles, or surgically removing them entirely. In later decades, the more drastic of these measures were increasingly replaced with psychological techniques, such as telling children they will get hairy hands or that their face will turn green from masturbating. In the United States and other English-speaking nations, routine neonatal circumcision was widely adopted in part because of its believed preventive effect against masturbation.
Some religious groups, such as the Catholics, the Church of Jesus Christ of Latter Day Saints, and the Muslims, teach masturbation to be a sinful practice. The Catechism of the Catholic Church, paragraph 2352, lists masturbation as one of the "Offenses Against Chastity" and calls it "an intrinsically and gravely disordered action" because "use of the sexual faculty, for whatever reason, outside of marriage is essentially contrary to its purpose." It goes on to caution that extenuating factors could exist, such as immaturity, habitual, or psychological problems.
During the Victorian Era in England, masturbation was strictly discouraged in children. Often, girls would be prevented from riding horses and bicycles because the sensations these activities produce were considered too similar to masturbation. Boys' pants were constructed so that the genitals could not be touched through the pockets. Surgical procedures and the use of restraining apparatuses were used as a last resort to prevent masturbation in children. These trends are in line with the widespread social conservatism and opposition to open sexual behavior common at the time.
Robert Baden-Powell, the founder of the Boy Scouts, incorporated a prohibition against masturbation in early scouting manuals, and into his eighties carried on correspondences with individual scouts exhorting them to control their urge for "self-abuse." He subscribed to the commonly held turn-of-the-century opinon that the practice led to disease, madness and sexual impotence. His views were not shared by all. Dr. F. W. W. Griffin, editor of The Scouter, wrote in 1930 in a book for Rover Scouts that the temptation to masturbate was "a quite natural stage of development" and steered scouts to a text by H. Havelock Ellis that held that "the effort to achieve complete abstinence was a very serious error."
St. Thomas Aquinas, one of the greatest theologians of the Catholic Church, went so far as to teach that masturbation is a graver sin than rape. In his masterwork, the Summa Theologica, he addresses the sin of lust under the heading of "Secunda Secundae Partis, Question 154." Under Article One, he divides the sin of lust into six categories: "the vice against nature," simple fornication, incest, adultery, seduction and rape. Under Article Eleven, the Angelic Doctor divides "the vice against nature" into four sub-categories: masturbation, zoophilia, homosexuality and non-procreative heterosexual sex. Finally, under Article Twelve, he explains that "the vice against nature," including masturbation, is clearly worse than the other five types of lust-based sins, for it is a sin against both nature and reason, whereas rape is merely a sin against reason alone. (See also II-II 153.) This hierarchy of sin was repudiated by the Catholic Church fairly recently; Pope Leo XIII (1810-1903) praised Aquinas' "invincible" arguments in his 1879 encyclical Aeterni Patris, claiming that "reason, born on the wings of Thomas, can scarcely rise higher, while faith could scarcely expect more or stronger aids from reason than those which she has already obtained through Thomas."
Most modern Protestant theologians have shunned these early teachings, and some even take pro-masturbation viewpoints.
Masturbation tends to be legal, even by children, as long as nobody else is involved and no image is made.
Masturbation in a public place, and in cases where somebody else is unexpectedly confronted with it, is indecent exposure. According to some historic chronicles, it has not always been so.
Laws may vary for masturbation as part of a performance, as visitor of a live or screen performance, as participant in a sex party, etc.
Because masturbation is often an uncomfortable topic among peers, a huge variety of euphemisms and dysphemisms have been invented to describe it. Some of the more common euphemisms are self-pleasuring, playing with oneself, and self-gratifying, all of which are gender-neutral, and fingering oneself, which is exclusively female. Common dysphemisms include fapping, touching yourself at night,jerking off , spanking hank, spanking the ham, flogging your log, buffing the knob, going to see rosey palm and her five daughters, meeting the bishop or the more descriptive bashing the bishop, polishing your musket, waxing your willy, whacking your jack, charming the one eyed python, going to see Aunt Mary and her four daughters, test-firing the purple-headed custard chucker, firing the pump-action yogurt rifle, cleaning your pipes, pounding your pud, lighting your wick, playing pocket pool, stroking it, pulling your goalie, wanking, jerking off, jacking off, pulling off, shaking hands with the sheriff, choking your chicken, jerkin' your gherkin, beating your meat, shaking hands with shorty, punching the clown, whacking off, killing some kittens, Shifting to fifth gear with Mr. Ho-Ho, firing the surgeon general, shaking hands with the minister of love, writing to your congressman, shaking hands with Abe Lincoln, windsurfing on Mount Baldy, doin' the janitor thing, punching the Munchkin, waxing the dolphin, killing the hermit (see KoL, wanking, spanking the monkey, rubbing one out, tickling your pickle, boil your noodle, beat around the bush, watering the garden, ground hog's day parade, hand surfing, pulling your wire (British & Commonwealth English, used particularly in Southern Africa) and clubbing the baby seal to describe male masturbation, and jilling off,flicking the bean, petting the kitty, flicking the bic, polishing the pearl or feeding the horse to describe female masturbation. Male masturbation in Cantonese translates as hitting the airplane. The Turkish expression translates literally to pull 31.
Ironically, the term frig which is often used as a 'polite' euphemism for the word fuck originally refers to female masturbation, but this is not so widely known.
Humor and masturbation
Masturbation, mainly male masturbation, has long been the subject of humour. Even in the early Twentieth Century, Mail Pouch Tobacco advertisements in some cases featured a boy baby reaching into his diaper, with the caption, "He's found his mail pouch."
In 1879, Mark Twain gave a humorous talk at the Stomach Club in Paris entitled Some Thoughts on the Science of Onanism, which concluded with the thought "If you must gamble your lives sexually, don't play a lone hand too much." This talk was not published until 1943.
Some famous wits have commented on masturbation, as in P. J. O'Rourke's quote: "Sophisticated persons masturbate without compunction. They do it for reasons of health, privacy, thrift and because of the remarkable perfection of invisible partners." Woody Allen, in the film "Annie Hall," insisted "Don't knock masturbation. It's sex with somebody I love."
Humorous songs have been written about masturbation, such as Chuck Berry's hit song, My Ding-a-ling. This song has no sexually explicit lyrics, but is clearly intended as a double entendre. Some other musical references to masturbation are the song "I Touch Myself" by Divinyls, sung in one of the final scenes in Austin Powers: International Man of Mystery, the Cyndi Lauper song "She Bop," and the 1970s disco song "Imaginary Lover" by Atlanta Rhythm Section.
There are much older songs on the subject, including this old parody on a classic operatic tune (sing to the tune of Funiculi, funicula):
- Last night, I lay my head upon my pillow,
- But stayed up late, to masturbate,
- Last night, I lay myself upon my bed, but
- I stayed awake, for pleasure's sake.
- You should see me working on the short strokes,
- It's really grand, I use my hand;
- You should see me working on the long strokes,
- It's really neat, I use my feet.
- Smash it! Bash it! Pound it on the floor!
- Smite it! Bite it! Ram it through the door!
- Oh, it's so neat to beat your meat while sitting on the toilet seat,
- Isn't life divine,
- Funiculi, funicula.
In recent years, there have been many masturbation jokes in movies, such as in American Pie, where the pie (more or less of the title) is used as a masturbation object to generate humor.
- DeMartino, Manfred F. Human Autoerotic Practices. New York: Human Sciences Press, 1979. ISBN 0877053731.
- Marcus, Irwin M. Masturbation: From Infancy to Senescence. New York: International Universities Press, 1975. ISBN 0823631508.