Sexual intercourse

Animals that reproduce sexually use sexual intercourse to have offspring. Sometimes sexual intercourse is called coitus or copulation and is more casually known as having sex or sleeping together. In sexual
intercourse, the male reproductive organ enters the female reproductive tract.[1][2] The two animals may be of opposite sexes or they may be hermaphroditic, as is the case with snails.[3]

Sexual intercourse between animals other than humans is often called mating. Most animals only mate when the female is at the point of estrus, which is the most fertile period of time in its reproductive cycle.[4][5]

In certain animals, sexual intercourse is not only used for reproduction, but has taken other functions as well. These animals include bonobos,[6] dolphins,[7] and chimpanzees which also have sexual intercourse even when the female is not in estrus, and to engage in sex acts with same-sex partners.[8] In most instances, humans have sex primarily for pleasure.[9] This behavior in the above mentioned animals is also presumed to be for pleasure,[10] which in turn strengthens social bonds.

Humans sometimes engage in behaviours that do not include the penetration of sexual organs, such as oral intercourse or anal intercourse or by non-sexual organs (fingering, fisting). These behaviours are sometimes included in the definition of sexual intercourse.[2]

Sexual intercourse with a partner of the same sex is called homosexual sex.

Forcing someone to have sex who does not want to, called rape, is a serious crime in many countries.
Contents

    1 Reproduction
    2 Behaviours unrelated to reproduction
    3 How humans prevent pregnancy
    4 Sexual orientation
    5 Sexually transmitted infections
    6 Sexual reproduction vs Asexual reproduction
    7 Other kinds of sex
        7.1 Oral sex
        7.2 Anal sex
        7.3 Painful sexual act
    8 Other pages
    9 Other websites
    10 References

Reproduction

    Main article: Sexual reproduction

Sexual intercourse is the natural and most common way to make a baby. It involves a man and woman having sex without birth control until the man ejaculates, or releases, semen from his penis into the woman's vagina. The semen, containing sperm (which is made in his testicles), moves to the Fallopian tubes, and if it finds an ovum on its way, it will try to fertilize it. If this works, the now fertilized ovum sticks to the side of the uterus and the woman becomes pregnant. The fertilized ovum then develops into a human. Medically, it is called a pregnancy until birth.
Behaviours unrelated to reproduction

Certain species of animals also have sex for other purposes than to bear offspring. These include Humans, bonobos,[6] chimpanzees and dolphins[7]. These species also are among those known to engage in homosexual behaviors.[8] In both humans and bonobos, the female has a relatively concealed ovulation. Neither male or female partners commonly know whether she is fertile at any given moment. One reason for this may be that sex partners of these species form strong emotional bonds. The partners come together for more than just sexual intercourse. In the case of humans, long-term partnership is more important than immediate sexual reproduction.[9]

Humans, bonobos and dolphins show cooperative behaviour. In many cases, this behaviour has shown better results than what an individual can achieve alone. In these animals, the use of sex has evolved beyond reproduction and has taken additional social functions. Sex reinforces intimate social bonds between individuals. Overall, such cooperation also benefits each member of the group in that they are better able to survive.

In humans, sexual intercourse seems to serve three types of purposes,which do not exclude one another:

    Reproduction
    Forming and keeping relationships
    Recreational[9][11]

How humans prevent pregnancy
Main page: Non-penetrative sex

In the late 20th century, very effective forms of contraception (birth control) were developed allowing a man and women to help prevent a baby from being made. One type of contraception is a condom. This is a piece of rubber that covers the penis that a man can wear during intercourse, which stops the man's semen from going into the woman's vagina. This does not always work though because the condom will rip or tear. Another well-known type of contraception is called the Pill, which a woman takes every day. When a woman is "on the Pill," she and her partner may have sex any time they wish with very little chance of making a baby. Contraception allows people to keep "sex for fun" separate from "sex to make children". For example, a fertile couple may use contraception to experience sexual pleasure (recreational). At the same time, this experience may strengthen their relationship, and a stronger relationship may mean that they will better be able to raise children in the future.
Sexual orientation

Who people like to have sex with depends on their sexuality. Men who like to have sex with women, and women who like to have sex with men are heterosexual or "straight". Men who only like to have sex with other men, and women who only like to have sex with other women are homosexual or "gay". A different word to describe a woman who only likes to have sex with other women is "lesbian". Some people like both men and women, which is called being bisexual. Approximately 1.5% of the Uk's population in 2010 was bisexual, gay or lesbian.
Sexually transmitted infections

    Main article: Sexually transmitted disease

Some diseases can be caught by having sex. These diseases are called sexually-transmitted infections (STIs).[12]

Some examples of STIs include chlamydia, syphilis and gonorrhoea. A virus called HIV causes AIDS, which cannot be cured and can lead to death.

Using Latex condoms or oral dams reduce the chance that a few types of diseases will be passed on, but it not entirely effective for all STIs. Birth control (like "the Pill") can prevent pregnancy, but won't prevent sexual infections.

Some STIs can also be spread in ways other than having sex. For example, herpes simplex and hepatitis B could be caught by a virgin without having sex, but can also be caught through sex. Some types of STIs can spread from contact between the genitals, mouth, anus, skin, eyes, and (rarely) infected surfaces; this depends a lot on the type of STI and how it spreads. Some common diseases like HPV can cause warts and cancer in the genitals or anus or throat.

There exists an HPV vaccine that prevents some sexually-transmitted strains of HPV; however, the vaccine only works if you get vaccinated before becoming infected. The vaccine is approved of for both men and women, but is often not required in the U.S. due to politics.
Sexual reproduction vs Asexual reproduction
Type     Advantages     Disadvantages
Asexual reproduction     No gestation period. No mate needed.     No variation in the species. No contact between the male and the female
Sexual reproduction     Variation of the species. Contact between male and female     Sometimes offspring are abnormal. Gestation period
Other kinds of sex

There are many other kinds of sex. Two of them are oral sex and anal sex.
Oral sex

Oral sex is when one partner uses the tongue, mouth, or throat to excite the other partner's sex organs.

Slang for oral sex is common in Western cultures, for example: "going down on", "giving a blowjob", or "giving head". The technical term for oral sex is fellatio if performed on a male and cunnilingus if performed on a female. When a man performs fellatio on himself, it is called autofellatio.

People can get sexually transmitted infections from oral sex, such as herpes (which can be passed between the mouth and groin), HIV and even oral cancer.
Anal sex

Anal sex is when an erect penis or other device made for sexual pleasure is inserted into the sexual partner's anus. Anal sex with a female does not lead to pregnancy by itself, however, semen can leak out of the anus and enter into the vagina, and pregnancy may rarely occur. Anal sex can still pass sexually transmitted diseases from one partner to another. It can also be very unhealthy for the body because the skin around the anus can tear, bleed and get infected with bacteria.[13] For safety and pleasure partners often use condoms, female condoms and/or lubrication.
Painful sexual act
Main page: Painful sexual act

A painful sexual act is a condition of repeated or persistent genital pain before, during, or after sexual intercourse due to physical, psychogenic and emotional causes. Doctors call the condition as "dyspareunia". It occurs in women and men. The condition affects up to one-fifth of women at some point in their lives.[14]