Most homosexual men with HIV became infected through sexual contact with other men, but there is nothing specifically "homosexual" about HIV/AIDS. Many men and women around the world have been infected with HIV through heterosexual contact. It appears that some factors, such as having another sexually transmitted disease like syphilis, or engaging in sexual practices that tear the skin lining of participants' sexual organs, may significantly facilitate infection occurring during sex.
Another common way HIV is transmitted is through injection drug use, specifically the sharing or reuse of hypodermic syringes or other injection paraphernalia. When drug users inject, their blood often enters the syringe. If they are infected with HIV, and should someone use this syringe after them, the virus may be transmitted via the syringe from the first to the second syringe user.
Other equipment used to inject illicit drugs, such as the "cooker" (usually a bottle cap or half of a soda can) in which drugs and water are mixed, may also serve as a route of HIV transmission when people "shoot up" drugs together.