If sex has to be explained to you, then you are either too young to be using a computer, or have been a member of sciforums so long that you have forgotten what it is.
Sex involves the transfer of semen into the vagina of receptive or drunk women, the rectum of men and women, or the oral cavities of both men and women. Sometimes bicycles , pavements, tree knots and the patio table  (the one with a hole for the patio umbrella) can be substituted for living breathing organisms. While dead people  make excellent receptacles, goats and chicken should not be overlooked  as possible sexual partners.
[Excerpt] - Sex also has many various conditions for each individual. Some so-called fetishes, are actually shared among a wide group throughout the world. Supersex is best felt, when no sex is ocurring. You can lye besides your partners arms, and its as though time itself dilates. But as much as it feels as though you have known them for all your life, even past lives... nothing escapes the inevitable conseuqence that one day they will die. The fear of death is what drives love. Life is short, and without a bit of stimulation, you can loose the one you might have wanted to meet, or as fate, a mythologically-coupled metaphysical arguement, that androgynous souls combine at death, to simple spirits in a state of limbo.