Sadomasochism is the giving or receiving of pleasure—sometimes sexual—from acts involving the infliction or reception of pain or humiliation. A subset of BDSM, practitioners of sadomasochism usually seek out sexual gratification from these acts, but can also seek out other forms of personal pleasure. While the terms sadist and masochist specifically refer to one who either enjoys giving pain (sadist), or one who enjoys receiving pain (masochist), many practitioners of sadomasochism describe, as can be found with the enjoyment of the experience in other fields of personal gratification activity, can have a spectrum or an activity switch, from someone being 100% active to 100% passive (although there is some reasonable assumption that a passive participant can become very involved in a scene).

The abbreviation S&M is often used for sadomasochism, although practitioners themselves normally drop the & and use the acronym SM or S/M. Sadomasochism is not considered a clinical paraphilia unless such practices lead to clinically significant distress or impairment for a diagnosis. Similarly, sexual sadism within the context of mutual consent should not be mistaken for acts of sexual violence or aggression.

Distinction among the subdivisions of BDSM

The term "Sadomasochism" has been loosely used to refer to the entire umbrella of BDSM. However, this is not accurate as BDSM is a shorthand for the three main subdivisions of the culture: B&D (bondage and discipline), D/s (dominance and submission) and S&M (sadism and masochism).

Bondage and discipline usually involves either physical or psychological restraint, formalized service or punishment, and sometimes sexual role playing, such as costumes.

(source: WiKiPedia)