Sex can be many things – passionate, intimate, fun, pleasurable, good exercise.
It can also be boring, painful, awkward or leave you wondering why you bothered.
It can take time to learn what you enjoy and what you don't. And it can often feel difficult or embarrassing to talk about sex with a partner.
So we're developing these pages with information and resources to help you enjoy sex – on your own or with a partner(s).
Masturbation (wanking, jerking off) is when you sexually arouse yourself by touching your genitals.
Some people also like to touch other areas of their body, such as the nipples, breasts or anus.
There's no right or wrong way to masturbate, as long as you're not doing anything you're uncomfortable with. When you’re masturbating on your own, it's all about you and what gives you pleasure.
If you're masturbating on your own then you're not at risk of pregnancy or a partner giving you a sexually transmitted infection so it is one of the safest sexual activities that you can do.
You might also choose to masturbate with a partner. This is a great opportunity to give pleasure to each other. It can be very sexy to watch a partner masturbate and this gives you the chance to see what turns them on too.
Read Masturbation Questions and Answers on the NHS Choices website.
Sexual arousal in men
When a man gets an erection, his body goes through four stages of sexual response: arousal, plateau, orgasm and resolution.
Stage 1: sexual excitement or arousal
A man gets an erection with physical or psychological stimulation, or both. This causes more blood to flow into three spongy areas called corpora that run along the length of his penis.
The skin is loose and mobile, allowing his penis to grow. His scrotum – the bag of skin holding the testicles – becomes tighter, so his testicles are drawn up towards the body.
Stage 2: sexual plateau
The head (glans) of his penis gets wider, and the blood vessels in and around the penis fill with blood. This causes the colour to deepen and his testicles to grow up to 50% larger.
His testicles continue to rise, and a warm feeling around the area between the testicles and anus (perineum) develops.
His heart rate increases, blood pressure rises, breathing becomes quicker, and his thighs and buttocks tighten. He's getting close to orgasm.
Stage 3: orgasm and ejaculation
A series of contractions force semen into the urethra, the tube along which urine and semen come out of the penis.
These contractions occur in the pelvic floor muscles, in the tube that carries sperm from the testicles to the penis (vas deferens).
They also occur in the seminal vesicles and the prostate gland, which both add fluid to the sperm. This mix of sperm (5%) and fluid (95%) is called semen.
These contractions are part of orgasm, and the man reaches a point where he can't stop ejaculation happening.
Contractions of the prostate gland and the pelvic floor muscles then lead to ejaculation, when semen is forced out of the penis.
Stage 4: resolution phase of sex
The man now has a recovery phase, when the penis and testicles shrink back to their normal size. He is breathing heavily and fast, his heart is beating rapidly, and he might be sweating.
There's a period of time after ejaculation when another orgasm isn't possible. This varies between men, from a few minutes to a few hours, or even days. The time generally gets longer as men get older.
If a man gets aroused but doesn't ejaculate, this resolution stage can take longer, and his testicles and pelvis might ache.
Find out more about penis health, including how to wash a penis and penis size.
If you have problems getting an erection or keeping an erection, find information at the Sexual Advice Association.
Find out more about male sexual problems.
Find sexual health services near you.
Sexual arousal in women
During arousal and sex, there are various stages of physical response. Researchers have identified four stages of sexual response in women and men: arousal, plateau, orgasm and resolution. This article describes what happens in a woman's body when she is sexually aroused
Stage 1: sexual excitement or arousal
When a woman becomes aroused (turned on), the blood vessels in her genitals dilate. There is increased blood flow in the vaginal walls, which causes fluid to pass through them. This is the main source of lubrication, which makes the vagina wet.
The external genitalia or vulva (including the clitoris, vaginal opening, and inner and outer lips or labia) become engorged (swollen) due to the increased blood supply. Inside the body, the top of the vagina expands.
The pulse and breathing quicken, and blood pressure rises. A woman may become flushed, especially on the chest and neck, due to the blood vessels dilating.
Stage 2: sexual plateau
Blood flow to the lower third of the vagina reaches its limit, and causes the lower area of the vagina to become swollen and firm. This is called the introitus, sometimes known as the orgasmic platform, and undergoes rhythmic contractions during orgasm.
A woman’s breasts may increase in size by up to 25%, and blood flow to the area around the nipple (the areola) increases, making the nipples look less erect.
As a woman gets closer to orgasm, her clitoris pulls back against the pubic bone and seems to disappear. Continuous stimulation is needed in this phase to build up enough sexual excitement for orgasm.
Stage 3: orgasm
Orgasm is the intense and pleasurable release of sexual tension that has built up in the earlier stages, characterised by contractions (0.8 seconds apart) of the genital muscles, including the introitus. Read more here: what is an orgasm?
Most women don’t experience the recovery period that men do after an orgasm. A woman may have another orgasm if she's stimulated again.
Not all women have an orgasm every time they have sex. For most women, foreplay is an important role in an orgasm occurring. This can include stroking erogenous zones and stimulating the clitoris.
Find out what can cause orgasm problems in women.
Stage 4: sexual resolution
This is when the woman's body slowly returns to its normal state. Swelling reduces, and breathing and heart rate slow down.