HIV is mainly transmitted through sexual contact between men of the same sex, and the chance of transmission between men of the same sex, especially men who have sex with men, is still relatively high. When gay men have anal sex, the epithelium of the mucous membrane in the rectum is more easily broken than the squamous epithelium in the vagina of women. Therefore, it is generally recommended for gay men to wear condoms when having sex. Condoms can effectively prevent the spread of HIV and significantly reduce the risk of HIV transmission. In addition to sexual contact, there are other ways of transmission, such as sharing razors, sharing intravenous injection supplies, etc., that may also carry the risk of HIV transmission.