Sexual desire is a motivational state and an interest in “sexual objects or activities, or as a wish, need, or drive to seek out sexual objects or to engage in sexual activities”. Sexual desire has been referred to by many different names such as libido, sexual drive, sexual motivation, sexual interest, and lust. an aspect of a person's sexuality, which varies significantly from one person to another, and also varies depending on circumstances at a particular time.
Sexual desire may be the “single most common sexual event in the lives of men and women”. Sexual desire is a subjective feeling state that can “be triggered by both internal and external cues, and that may or may not result in overt sexual behaviour”. Sexual desire can be aroused through imagination and sexual fantasies, or perceiving an individual that one finds attractive.
Sexual desire can be spontaneous or responsive. Sexual desire is dynamic, can either be positive or negative, and can vary in intensity depending on the desired object/person. The sexual desire spectrum is described by Stephen B. Levine as: aversion --> disinclination --> indifference --> interest --> need --> passion.
The production and use of sexual fantasy and thought is an important part of properly functioning sexual desire. Some physical manifestations of sexual desire in humans are; licking, sucking, puckering, and touching the lips, as well as tongue protrusion.