Autoeroticism or autosexuality is a practice of sexually stimulating oneself, especially one's own body through accumulation of 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 person".

The most common autoerotic practice is masturbation. Though the terms autoeroticism and masturbation are often used interchangeably, they are not synonymous as not all autoerotic behaviors are masturbatory. Nocturnal emissions, erotic daydreams, and sexual arousal to 'sexually-neutral' stimuli (music, scenery, art, risk, spiritual reverie, etc.) are also examples of autoeroticism.