HIV and men who have sex with men sexual activity with members of the same sex, regardless of how they personally identify themselves. Many MSM choose not to (or cannot for other reasons) identify as homosexual or bisexual. Similarly, the label excludes men who identify as gay or bisexual, but who have never had sex with another man, including many gay teenagers. The terms MSM and women who have sex with women (WSW) have been used in medical scholarship since at least 1990. But, the term has been attributed to Glick "et al.", because their usage in a 1994 study solidified the concept in medical terminology. MSM is
Men who have sex with men figures include victims of sexual abuse in addition to men who regularly or voluntarily have sex with men. In the U.S., among men aged 15 to 44, an estimated 6% have engaged in oral or anal sex with another man at some point in their lives, and about 2.9% have had at least one male sexual partner in the previous 12 months. Historically, anal sex has been popularly associated with male homosexuality and MSM. However, many MSM do not engage in anal sex, and may engage in oral sex, frotting or mutual masturbation instead. Among men who have anal sex