It seems reasonable to define abnormal sexual behavior as behavior that is uncomfortable for the person, inefficient, bizarre, or physically or psychologically harmful to the person or others. The American Psychiatric Association defines paraphilias as recurrent, intense, sexually arousing fantasies, urges, or behaviors that are obsessive and compulsive.

Four theoretical approaches have been used in understanding the paraphilias: learning theory, cognitive theory, the sexual addiction model, and sociological theory. Several explanations have been proposed for the fact that there are many more male than female paraphiliacs.

A fetishist is a person who becomes erotically attached to some object other than another human being. Most likely, fetishism arises from conditioning, and it provides a good example of the continuum from normal to abnormal behavior.

The transvestite derives sexual satisfaction from dressing as a member of the other gender. Like many other sexual variations, transvestism is much more common among men than among women. Survey data suggest that many men who later become transvestites begin cross-dressing in childhood.

Three styles of sexual interaction involve differences in control over sexual interactions. Dominance and submission involve a consensual exchange of power, and the enacting of scripted performances. Bondage and discipline involve the use of physical restraints or verbal commands by one person to control the other. Both D-S and B-D may occur without genital contact or orgasm. Sadism and masochism involve deriving sexual gratification from giving and receiving pain. Both are recognized as paraphilias if they become compulsive.

The voyeur is sexually aroused by looking at nudes. The exhibitionist displays his or her sex organs to others. Both are generally harmless.

Nymphomania and satyriasis are terms used to describe women and men with an extraordinarily high sex drive. Both terms are ambiguous and subject to misuse. The term hypersexuality is potentially more precise, particularly if it is defined behaviorally.

Other sexual variations include asphyxiophilia, zoophilia, and necrophilia. A recent concern is cybersex abuse, which is facilitated by the anonymity, accessibility and affordability of the Net.

The possibility of programs to prevent sexual variations is being explored. Available programs include medical treatments, cognitive-behavioral therapies, skills training, and AA-type 12-step programs. We need careful research to determine which programs work best in the treatment of given behaviors.