Sadomasochism is a paraphilia that combines both sadistic and masochistic sexual behavioral patterns. The main characteristic of sadomasochism is the eroticizing of pain.

What appears to the outsider to be painful, even very painful, is experienced as somewhat painful but mostly pleasurable and very sexually arousing to the sadomasochist.

The sadist in the sadomasochistic pair is the person who inflicts the pain or punishment; the masochist is the person who submits to the pain, humiliation or control of his or her partner.

Sadomasochistic sexual encounters usually occur in the context of scripted scenes that simulate interactions between master or mistress and slave, employer and servant-maid, teacher and student, owner and horse or dog, and parent and child.

Sadomasochists may wear black leather or rubber attire. Some gay males and heterosexuals engage in a genre of sadomasochism known as "leathersex", wearing key chains or colored handkerchiefs symbolizing the role being played. Wearing keys on the left side indicates that the individual is a sadist; on the right indicates that he or she prefers the role of masochist.

Alternating Roles
Sadomasochists tend to alternate between the masochistic and sadistic roles. In milder form, without overt cruelty or bodily punishment, dominance and submissive behaviors may be found in many relationships, or may be an element of fantasy life.

Although sadomasochistic acts in their extreme forms can be physically and psychologically dangerous, the majority of people engaging in these behaviors do so with an understanding of the risks and stay within carefully predetermined limits.