Short answers, pulled from the story.
Sexual intercourse, also called coitus or copulation, is penetrative sexual activity carried out for reproduction, pleasure, or both. While it most commonly means penile-vaginal penetration, it also includes anal sex, oral sex, fingering, and penetration using devices such as dildos and vibrators.
Researchers most often use sexual intercourse to mean penile-vaginal penetration because of what scholars Richard M. Lerner and Laurence Steinberg call the larger culture's preoccupation with that form of activity. This focus can demote other forms of sex to mere foreplay and narrows what the law is willing to count as rape.
Correct and consistent use of latex condoms reduces the risk of HIV transmission by approximately 85 to 99 percent compared with unprotected sex, according to reports from the National Institutes of Health and the World Health Organization. Condoms are rarely used for oral sex, and abstaining from vaginal, anal, and oral intercourse remains the most effective way to avoid sexually transmitted infections.
Pregnancy rates are highest from roughly five days before ovulation until about one day after, a span sometimes called the fertile window. Recommendations for conception include vaginal intercourse every one to two days, or every two to three days, and sex position makes no significant difference as long as ejaculation reaches the vagina.
About 40 percent of men report some form of erectile dysfunction at least occasionally, and the American Urological Association estimates premature ejaculation affects 21 percent of men in the United States. Among women, roughly 25 percent report difficulty reaching orgasm, 10 percent have never had one, and 40 to 50 percent report sexual dissatisfaction or trouble becoming aroused at some point.
In 2012 the Federal Bureau of Investigation replaced its older definition, the carnal knowledge of a female forcibly and against her will, with a broader one. The new wording covers penetration of the vagina or anus by any body part or object, and oral penetration by a sex organ, without the victim's consent, allowing rape to be reported more accurately nationwide.
Yes. Bonobos, chimpanzees, and dolphins are known to engage in sexual behavior even when the female is not in estrus, and to engage in same-sex sexual behavior. In these species, intercourse has evolved beyond reproduction to serve additional social functions such as bonding.