A deliberate thought of being in a particular sexual situation, where one becomes aroused by the conscious thought.
To conjure up a mental image, whether asleep or awake, of engaging in specific sexual situations, that one wishes for, or would seek to experience, but not necessarily in actuality.
A vivid mental image of sexual activity, which generally evolves from being in a specific situation that leads to the actual sexual relation, which does not always involve intercourse, or penetration.
Sexual Fantasy acceptance is rather new, specially in the Western World, where morals are vastly different than in other cultures. In less modern times, sexual fantasies were considered improper, and signs of deviant behavior or of being under the influence of dark agents, such as the Devil.
Many ancient cultures considered sexual fantasies to be sinful, or of a person being under the influence of evil demons.
Many under Christian Rule were of the opinion that sexual fantasies were immoral, due to the scriptures of Mathew 5:28. It was thought that thinking of others, who were not yours, was immoral. Should be noted that wives were considered one's property at the time.
Prior to the 20th Century, many considered sexual fantasies as abnormal, specially in women. In some instances, leading psychologists considered sexual fantasies in women as being a form of hysteria.
As a result of this negative perception, most sexual fantasies were kept private, and in some cultures today, still remain taboo subjects for discussion, or revelation.
Erotic fantasies can occur at any time, triggered by any particular sight, smell, or taste. Usually it occurs while awake, where a person will fantasize about some situation, due to circumstances. It can also occur during sex with another, or during masturbation.
Most 'thoughts' are of sexual acts, or of ignoring particularly distasteful side effects of a sex act. For example, rimming might not be considered pleasant, due to the odor or such, but instead of thinking of that aspect of it, a person will think of how it makes them feel, or how it makes their partner react.
Other aspects of sexual fantasies is about placing one in a position that they would normally not be in, hence dreams of a more violent nature can occur, leading to heighten sexual reactions.
Some will dream of scenes of violence, of rape, which they would never actually do, or participate in, yet they will fantasize about it, experiencing it within their mind.
It is more common for men, during jerking off, fellatio, to have sexual fantasies.
Practice (Associated Acts): During actual sex, many will use fantasies to allow them to receive or participate in particular sexual acts. It is this mental ability to zone out, or turn to alternative thoughts, that enables them to enjoy a particular sexual experience.
Such as a man thinking his partner is younger, has different features, or a woman concentrating on the feelings, instead of worrying about any particular body odor, while engaged in cunnilingus.
Noteworthy: While some couples will share their feelings, their fantasies, as a form of bonding, others will keep them secret, feeling shame, or guilt for having them. In those instances, the quality of their sexual relations can suffer.
The most common types of fantasies are of imagining sex with a current partner, a different partner, or of a past sexual encounter.
Fantasies are used to escape the normal life situations, where a person will imagine themselves in different roles, such as being compliant, when they are a dominant personality, or of being dominant, when normally they are submissive.
Most do not act out their sexual fantasies, though some tend to develop an obsession, that leads them to blur the line between reality, and fantasy.
In some instances, sexual fantasies are used to plan future sexual encounters, or to help create future sexual encounters. This is generally in a non threatening way, such as thinking of how they will respond in a bar to an advance from someone they desire, or how they would approach such a person.