The term's precise use and definition has varied with regard to trans women, people born either biologically male or with ambiguous genitalia who self-identify as female. In some countries, homosexual relationships may be illegal or taboo, making MSM difficult to reach.
There were no similar traits in all of the MSM population studied, other than them being males and engaging in sex with other men. In their assessment of the knowledge about the sexual networks and behaviors of MSM in Asia, Dowsett, Grierson and McNally concluded that the category of MSM does not correspond to a single social identity in any of the countries they studied. Men who are non-heterosexual or questioning may identify with all, none, a combination of these, or one of the newer terms indicating a similar sexual, romantic, and cultural identity like bi-curious. Gay is a social identity and is generally the preferred social term, whereas homosexual is used in formal contexts, though the terms are not entirely interchangeable. Homosexuality refers to sexual/romantic attraction between members of the same sex and may or may not include romantic relationships. MSM refers to sexual activities between men, regardless of how they identify, whereas gay can include those activities but is more broadly seen as a cultural identity. MSM and gay refer to different things: behaviors and social identities. MSM are not limited to small, self-identified, and visible sub-populations. The Huffington Post postulates that the term MSM was created by Cleo Manago, the man who is also credited for coining the term same gender loving (SGL). Second, its usage is tied to criticism of sexual identity terms prevalent in social construction literature which typically rejected the use of identity-based concepts across cultural and historical contexts. First, it was pursued by epidemiologists seeking behavioral categories that would offer better analytical concepts for the study of disease-risk than identity-based categories (such as "gay", " bisexual", or "straight"), because a man who self-identifies as gay or bisexual is not necessarily sexually active with men, and someone who identifies as straight might be sexually active with men. in 1994 "signaled the crystallization of a new concept." This behavioral concept comes from two distinct academic perspectives. The term MSM had been in use in public health discussions, especially in the context of HIV/AIDS, since 1990 or earlier, but the coining of the initialism by Glick et al.
5 MSM blood and tissue donor controversy.4.1.2 Other sexually transmitted infections.1.1 As applied to transgender individuals.