Fifty Shades of Gray opened this topic to the main stream public, a very old practice and very common in some sectors. No one thought that such an attractive guy could take pleasure in pain. But ... Do you know how much is practiced in real life?
Sadism is the obtaining of pleasure when performing acts of cruelty or mastery, and masochism from receiving these acts. If it is consensual and sexual it is considered a paraphilia part of BDSM (Bondage, discipline, dominion and submission, sadism and masochism). Paraphilias are different forms of pleasure, and vary from the provocation of pain, to seeing someone crying, to feeling certain textile textures, to the presence of certain animals. There are as many paraphilias as human diversity although some have not been recognized. Each one has different sexual triggers that bring pleasure and light the flame of passion.
Although it is difficult to obtain reliable data on its practice, surveys were carried out in Spain in 1999 to measure it. In these, 23% of men and 19% of women admitted to having performed some BDSM activity, and 33% and 45% respectively have fantasized about it, which could indicate a propensity in the female population. In general, males said they had a greater preference for dominance (sadism) and women for submission (masochism), although both groups had practitioners on both sides, as well as switchers, who like to change roles.
Specifically speaking of biting, biting the sexual partner, it has been found by the Kinsey Institute that little more than half of the population feels pleasure when being bitten during sex.
BDSM has been indexed for over a century in "The Diagnostic and Statistical Manual of Mental Disorders," edited by the American Psychiatric Association. The latest edition is DSM-5 published in 2013 and still contemplates them. Since 1990 homosexuality was officially removed from this list. Some hope that different paraphilias will be discarded in the same way.
The interesting thing is to know that there is a great variety of tastes and pleasures and that each and every one is free to express itself when there is an agreement between both parties. This also shows how many fantasies can be repressed by morality or fear of criticism. Overall, we do not know what we like and what not until we don't experience it. It is a matter of each person as they want to live their sex life.