The prevalence of fetishism is not known with certainty. The majority of fetishists are male. In a 2011 study, 30% of men reported fetishistic fantasies, and 24.5% had engaged in fetishistic acts. Of those reporting fantasies, 45% said the fetish was intensely sexually arousing. In a 2014 study, 26.3% of women and 27.8% of men acknowledged any fantasies about "having sex with a fetish or non-sexual object". A content analysis of the sample's favorite fantasies found that 14% of the male fantasies involved fetishism (including feet, nonsexual objects, and specific clothing), and 4.7% focused on a specific body part other than feet. None of the women's favorite fantasies had fetishistic themes. Another study found that 28% of men and 11% of women reported fetishistic arousal (including feet, fabrics, and objects "like shoes, gloves, or plush toys"). 18% of men in a 1980 study reported fetishistic fantasies.

Fetishism to the extent that it becomes a disorder appears to be rare, with less than 1% of general psychiatric patients presenting fetishism as their primary problem. It is also uncommon in forensic populations.

Research has shown that paraphilias are rarely observed in women. However, there have been some studies on females with paraphilias. Sexual masochism has been found to be the most commonly observed paraphilia in women, with approximately 1 in 20 cases of sexual masochism being female.

Many acknowledge the scarcity of research on female paraphilias. The majority of paraphilia studies are conducted on people who have been convicted of sex crimes. Since the number of male convicted sex offenders far exceeds the number of female convicted sex offenders, research on paraphilic behavior in women is consequently lacking. Some researchers argue that an underrepresentation exists concerning pedophilia in females. Due to the low number of women in studies on pedophilia, most studies are based from "exclusively male samples". This likely underrepresentation may also be attributable to a "societal tendency to dismiss the negative impact of sexual relationships between young boys and adult women". Michele Elliott has done extensive research on child sexual abuse committed by females, publishing the book "Female Sexual Abuse of Children: The Last Taboo" in an attempt to challenge the gender-biased discourse surrounding sex crimes. John Hunsley states that physiological limitations in the study of female sexuality must also be acknowledged when considering research on paraphilias. He states that while a man's sexual arousal can be directly measured from his erection (see penile plethysmograph), a woman's sexual arousal cannot be measured as clearly (see vaginal photoplethysmograph), and therefore research concerning female sexuality is rarely as conclusive as research on men.

Fetishism usually becomes evident during puberty, and may develop prior to that. No cause for fetishism has been conclusively established.

Some explanations invoke classical conditioning. In several experiments, men have been conditioned to show arousal to stimuli like boots, geometric shapes or penny jars by pairing these cues with conventional erotica. According to John Bancroft, conditioning alone cannot explain fetishism, because it does not result in fetishism for most people. He suggests that conditioning combines with some other factor, such as an abnormality in the sexual learning process.

Theories of sexual imprinting propose that humans learn to recognize sexually desirable features and activities during childhood. Fetishism could result when a child is imprinted with an overly narrow or "incorrect" concept of a sex object. Imprinting seems to occur during the child's earliest experiences with arousal and desire, and is based on "an egocentric evaluation of salient reward- or pleasure-related characteristics that differ from one individual to another."

Neurological differences may play a role in some cases. Vilayanur S. Ramachandran observed that the region processing sensory input from the feet lies immediately next to the region processing genital stimulation, and suggested an accidental link between these regions could explain the prevalence of foot fetishism. In one unusual case, an anterior temporal lobectomy relieved an epileptic man's fetish for safety pins.

Various explanations have been put forth for the rarity of female fetishists. Most fetishes are visual in nature, and males are thought to be more sexually sensitive to visual stimuli. Roy Baumeister suggests that male sexuality is unchangeable, except for a brief period in childhood during which fetishism could become established, while female sexuality is fluid throughout life.

Paraphilia (previously known as sexual perversion and sexual deviation) is the experience of intense sexual arousal to atypical objects, situations, fantasies, behaviors, or individuals. Such attraction may be labeled sexual fetishism. No consensus has been found for any precise border between unusual sexual interests and paraphilic ones. There is debate over which, if any, of the paraphilias should be listed in diagnostic manuals, such as the "Diagnostic and Statistical Manual of Mental Disorders" (DSM) or the International Classification of Diseases (ICD).

The number and taxonomy of paraphilia is under debate; one source lists as many as 549 types of paraphilia. The DSM-5 has specific listings for eight paraphilic disorders. Several sub-classifications of the paraphilias have been proposed, and some argue that a fully dimensional, spectrum or complaint-oriented approach would better reflect the evidence.

Transvestism is the practice of dressing and acting in a style or manner traditionally associated with the opposite sex. In some cultures, transvestism is practiced for religious, traditional or ceremonial reasons.

The following are some of the partialisms commonly found among people:

Some types of BDSM play include, but are not limited to:

- Animal roleplay

- Bondage

- Breast torture

- Cock and ball torture (CBT)

- Erotic electrostimulation

- Edgeplay

- Flogging

- Golden showers (urinating)

- Human furniture

- Japanese bondage

- Medical play

- Paraphilic infantilism

- Predicament bondage

- Pussy torture

- Sexual roleplay

- Spanking

- Suspension

- Torture

- Tickle torture

- Wax play

In 2007, a study was conducted by the University of Bologna on around 5000 fetishist participants to see the prevalence of fetishes. The study analyzed the content inside online fetish communities and found only 669 participants referring to nails, an extension of hand fetishism. This did not refer to fingernails specifically, and the amount of 669 was less than 1% of the participants.

Diaper fetishists and diaper lovers (DLs) are often associated with adult babies, as both wear diapers, but the former do not engage in childlike behavior, while that is the distinguishing characteristic of adult babies (ABs). The majority of diaper lovers do not engage in any kind of infantile activity and are only interested in diapers. However, in certain individuals it is possible for an overlap to occur, as one can view themselves as neither exclusively an adult baby nor a diaper lover. Hence adult babies and diaper lovers collectively refer to themselves as AB/DLs. Diapers and rubber pants with "baby" prints are sold in adult sizes.

The Internet has enabled people with this relatively rare paraphilia to discuss the subject and exchange anesthesia-related multimedia.

Medical fetishism refers to a number of sexual fetishes involving objects, practices, environments, and situations of a medical or clinical nature. In sexual roleplay a hospital or medical scene involves the sex partners assuming the roles of doctors, nurses, surgeons and patients to act out specific or general medical fetishes. Medical fantasy is a genre in pornography, though the fantasy may not necessarily involve pornography or sexual activity.

Medical fetishism may involve sexual attraction to respiratory therapy involving oxygen via nasal cannula or any sort of masks, medical practitioners, medical uniforms, hospital gowns, anaesthesia, intimate examinations (such as rectal examination, gynecological examination, urological examination, andrological examination, rectal temperature-taking), catheterization, diapering, enemas, injections, insertion (such as suppository insertion, menstrual-cup insertion, and prostatic massage), medical devices (such as orthopedic casts and orthopedic braces; see also "Abasiophilia"), dental objects (such as dental braces, retainers, and headgear), medical restraints, and medical gags.

Hand fetishism or hand partialism or also Quirofilia is the sexual fetish for hands. This may include the sexual attraction to a specific area such as the fingers, palm or nails, or the attraction to a specific action performed by the hands; which may otherwise be considered non-sexual—such as washing or drying dishes. This fetish may manifest itself as a desire to experience physical interaction, or as a source of sexual fantasy.

Hand fetishism is recognized by the porn industry; however, it is one of the least common fetishes, despite foot fetishism being the most common.

Hand fetishism is usually based in the biological indication that a partner is healthy and a good potential mate.

Males with late onset gender dysphoria "frequently" display transvestic fetishism.

Some male transvestic fetishists collect women's clothing, e.g. panties, nightgowns, babydolls, bridal gowns, slips, brassieres, and other types of nightwear, lingerie, stockings, pantyhose, shoes, and boots, items of a distinct feminine look and feel. They may dress in these feminine garments and take photographs of themselves while living out their fantasies.

According to DSM-IV, this fetishism was limited to heterosexual men; however, DSM-5 does not have this restriction, and opens it to women and men with this interest, regardless of their sexual orientation.

There are two key criteria before a psychiatric diagnosis of "transvestic fetishism" is made:

1. Individuals must be sexually aroused by the act of cross-dressing.

2. Individuals must experience significant distress or impairment – socially or occupationally – because of their behavior.

Diaper fetishism, nappy fetishism or diaperism, is a type of garment fetish or paraphilic infantilism. A person with a diaper fetish derives pleasure from the diaper and/or use of it. Being forced to wear diapers as a form of humiliation is sometimes a behavior encountered in sexual masochism.

It is important to note that the diaper fetish community actively opposes and condemns child molesters. Both men and women can practice diaper fetishes, both inside and outside a relationship. As of September 2015, Huffington Post Arts & Culture published an interview on diaper fetishes that was widely regarded as informative within the community. While this clothing fetish is obscure, diaper fetishists engage in the behavior privately or with a partner who shares a mutual interest in the fetish.

A fetish (derived from the French "fétiche"; which comes from the Portuguese "feitiço"; and this in turn from Latin "facticius", "artificial" and "facere", "to make") is an object believed to have supernatural powers, or in particular, a human-made object that has power over others. Essentially, fetishism is the emic attribution of inherent value or powers to an object.

Low sexual desire alone is not equivalent to HSDD because of the requirement in HSDD that the low sexual desire causes marked distress and interpersonal difficulty and because of the requirement that the low desire is not better accounted for by another disorder in the DSM or by a general medical problem. It is therefore difficult to say exactly what causes HSDD. It is easier to describe, instead, some of the causes of low sexual desire.

In men, though there are theoretically more types of HSDD/low sexual desire, typically men are only diagnosed with one of three subtypes.

- Lifelong/generalised: The man has little or no desire for sexual stimulation (with a partner or alone) and never had.

- Acquired/generalised: The man previously had sexual interest in his present partner, but lacks interest in sexual activity, partnered or solitary.

- Acquired/situational: The man was previously sexually interested in his present partner but now lacks sexual interest in this partner but has desire for sexual stimulation (i.e. alone or with someone other than his present partner.)

Though it can sometimes be difficult to distinguish between these types, they do not necessarily have the same cause. The cause of lifelong/generalized HSDD is unknown. In the case of acquired/generalized low sexual desire, possible causes include various medical/health problems, psychiatric problems, low levels of testosterone or high levels of prolactin. One theory suggests that sexual desire is controlled by a balance between inhibitory and excitatory factors. This is thought to be expressed via neurotransmitters in selective brain areas. A decrease in sexual desire may therefore be due to an imbalance between neurotransmitters with excitatory activity like dopamine and norepinephrine and neurotransmitters with inhibitory activity, like serotonin. The, New York-based, "New View Campaign" organization has expressed skepticism about too much emphasis on explanations based on neurotransmitters because emphasis on such explanations have been made largely by "educational" efforts funded by Boehringer-Ingelheim while it was attempting to get the FDA to approve a drug affecting neurotransmitters for treatment for HSDD. Low sexual desire can also be a side effect of various medications. In the case of acquired/situational HSDD, possible causes include intimacy difficulty, relationship problems, sexual addiction, and chronic illness of the man’s partner. The evidence for these is somewhat in question. Some claimed causes of low sexual desire are based on empirical evidence. However, some are based merely on clinical observation. In many cases, the cause of HSDD is simply unknown.

There are some factors that are believed to be possible causes of HSDD in women. As with men, various medical problems, psychiatric problems (such as mood disorders), or increased amounts of prolactin can cause HSDD. Other hormones are believed to be involved as well. Additionally, factors such as relationship problems or stress are believed to be possible causes of reduced sexual desire in women. According to one recent study examining the affective responses and attentional capture of sexual stimuli in women with and without HSDD, women with HSDD do not appear to have a negative association to sexual stimuli, but rather a weaker positive association than women without HSDD

Macrophilia is a fascination with or a sexual fantasy involving giants, more commonly expressed as giantesses (female giants). It is typically a male fantasy, with the male playing the "smaller" part—entering, being dominated, or being eaten by the larger woman. Others involve partners who naturally have a significant difference in size.

Gender identity is a concept, specifically psychological, that refers to one's sense of being a male or female in regards to sexual orientation. Individuals who are diagnosed with gender identity disorder are classified as being dissatisfied with their anatomically determined gender.

Although macrophilia literally translates to simply a "lover of large," in the context of a sexual fantasy, it is used to mean someone who is attracted to beings larger than themselves. Generally, the interest differs between people, and depends on gender and sexual orientation. They often enjoy feeling small and being abused, degraded, dominated, or eaten, and they may also view female giants as being powerful and dominating.

Commenting on why there are not as many female macrophiles, psychologist Helen Friedman theorized that because women in most societies already view men as dominant and powerful, there is no need for them to fantasize about it. Women that take on the roles of the giantess within this fetish often find the practice to be empowering and enjoy being worshipped.

The roots of macrophilia may lie in sexual arousal in childhood and early adolescence which is accidentally associated with giants, according to Dr. Mark Griffiths's speculation.

Acrotomophilia (from the Greek ἀκρότομος "having the top cut off" (from ἄκρον "akron" "extremity" and -τομος "-tomos" from τέμνω "temno" "I cut") and φιλία "philia" "love") is a paraphilia in which an individual expresses strong sexual interest in amputees. It is a counterpart to "apotemnophilia", the sexual interest in "being" an amputee.

Acrotomophiles may be attracted to amputees because they like the way they look or they may view the amputee’s stump as a phallic object which can be used for sexual pleasure.A small number of Acrotomophiles may enjoy the idea of dominating the amputee during couples play and they may also become aroused with the thought of having to take care of an amputee.

Erotophobia is a term coined by a number of researchers in the late 1970s and early 1980s to describe one pole on a continuum of attitudes and beliefs about sexuality. The model of the continuum is a basic polarized line, with erotophobia (fear of sex or negative attitudes about sex) at one end and erotophilia (positive feelings or attitudes about sex) at the other end.

The word erotophobia is derived from the name of Eros, the Greek god of erotic love, and Phobos, Greek (φόβος) for "fear".

Transvestic fetishism is a psychiatric diagnosis applied to those who are thought to have an excessive sexual or erotic interest in cross-dressing; this interest is often expressed in autoerotic behavior. It differs from cross-dressing for entertainment or other purposes that do not involve sexual arousal, and is categorized as a paraphilia in the Diagnostic and Statistical Manual of the American Psychiatric Association. (Sexual arousal in response to donning sex-typical clothing is homeovestism.)

HSDD was listed under the Sexual and Gender Identity Disorders of the DSM-IV. In the DSM-5, it was split into male hypoactive sexual desire disorder and female sexual interest/arousal disorder. It was first included in the DSM-III under the name inhibited sexual desire disorder, but the name was changed in the DSM-III-R. Other terms used to describe the phenomenon include sexual aversion and sexual apathy. More informal or colloquial terms are "frigidity" and "frigidness".

Mysophilia relates to soiled or dirty material or people. Mysophiliacs may find dirt, soiled underwear, feces, or vomit to be sexually arousing.

It is possible for people with mysophilia to be aroused by unclean locales, such as an alleyway, or a dirty room/bathroom; wearing the same clothing for many days at a time; or not bathing, from mere days to several weeks.