The penis is a sex organ which is partly inside and outside of the body and used for sex as well as urinating (going to the toilet). The penis reaches its full size during puberty and all penis vary in shape and size.
Understanding different parts of the penis
The foreskin is a sleeve of skin that surrounds the head of the penis. When you get an erection, the foreskin stretches. The head of the penis is then completely exposed. In some cases, the foreskin can be tight. If there seems to be a problem and it is uncomfortable when the foreskin stretches you should consider talking to a doctor.
Circumcision is the removal of the foreskin, it is a simple operation and may be done for religious or medical reasons, but it doesn't affect the way the penis works.
Testicles and the scrotum
Testicles, (testes, balls), hang in a bag (scrotum) outside the body, just behind the penis. They produce sperm (cum). The scrotum hangs outside the body because sperm need to be kept cooler than your internal body temperature of 37C. The scrotum is usually darker in colour than the rest of the skin, and has hair on it. When it's cold, the scrotum can become wrinkled but when it is warm, the balls hang loose, and the surface of the scrotum is smooth.
Spots, bumps and moles are common on the scrotum and penis, and don't usually mean anything.If you play a sport where a blow, boot, or ball could damage your testicles, wear a plastic protector or shield.
Semen is a combination of seminal fluid and sperm and is usually white/yellow milky liquid in which the sperm swim. When a sperm fertilises an egg this is how a person becomes pregnant. When a man ejaculates, he releases on average a teaspoon of semen containing up to 300 million sperm. Some men can come several times a day, others, fewer times.
What is an erection?
An erection (hard-on/ boner) is caused by blood filling the penis and causing it to stretch in shape and size. This makes the penis become larger and harder and it stands out from the body. Erections can happen for many reasons but are usually caused by some sort of sexually arousing thoughts or stimulation (such as touching).
When your penis is erect, you can't urinate (go to the bathroom) easily because a muscle closes the bladder off. The shape of an erect penis varies. It usually curves upwards slightly, and may point to the one side. Erections occur in males of all ages, including babies and older men.
Erections can come and go without warning. They can happen at a moment's notice, sometimes in embarrassing circumstances. Many factors can influence the ability to get an erection such as being nervous, upset or drunk. If you get an erection when you don't want one there are things you can do to make it go away. Try to relax and focus your mind on something other than your erection.
Most young men ejaculate (cum, come, have an orgasm) for the first time between the ages of 10 and 18, usually at age 13 or 14. It takes some by surprise–others work at it. Sexual excitement causes muscles at the base of the penis to contract hard and semen to spurt out. During a man's orgasm, about 3 to 15 contractions occur. Each lasts about a second. The first three or so are usually the most intense. Sometimes ejaculation may pump semen quite a distance. At other times, it just dribbles out. Semen may be thick and almost yellow or thin and watery.
Most men rub themselves to get an erection and to have an orgasm, this is called masturbation. Masturbation (wanking) leads to ejaculation and is normally harmless, no matter how often you masturbate. One slight danger with masturbation is infection if you masturbate with something unclean. Also, you may irritate your sex organs by rubbing too hard for too long. If that happens, stop. Masturbation helps you to know your body better, and what you like and don't like. If you are experiencing pain when masturbating you should think about visiting a doctor.
Wet dreams are when you ejaculate in your sleep. You may be embarrassed when you have a wet dream, but it's totally normal. All boys have them and they usually stop as you mature physically.
Premature ejaculation occurs when a man ejaculates before or immediately after penetration in intercourse (sex). It happens a lot more in young men who have not been having sex for a very long time or who have not done it for a while. It can be due to excitement. Using a condom can help. If you are experiencing premature ejaculation problems over a long period you should consider speaking to your doctor about it.
Condoms are the most effective way to protect yourself from sexually transmitted infections (STIs) during vaginal sex, anal sex, or oral sex performed on a penis. They are also an effective contraceptive for preventing pregnancy. Read our article on How to use a condom for advice on where to buy them, when to use them and how to put them on.