Autoeroticism is the practice of becoming sexually stimulated through internal stimuli. The term was popularized toward the end of the 19th century by British sexologist Havelock Ellis, who defined autoeroticism as "the phenomena of spontaneous sexual emotion generated in the absence of an external stimulus proceeding, directly or indirectly, from another [animate entity]." The most common autoerotic practice is masturbation, and though the two terms are often used synonymously, there is an inequality. Not all autoerotic behaviors are masturbatory behaviors. Nocturnal emissions, erotic daydreams, and sexual arousal to 'sexually-neutral' stimuli (music, scenery, art, risk, spiritual reverie, etc.) are examples of autoeroticism.
