High-risk sex refers to sex that is prone to sexually transmitted diseases. During high-risk sex, one will come into contact with the other’s secretions, body fluids and so on, and if there is skin damage to the genitals, one may also come into contact with the other’s blood, so it is very easy for many infectious diseases to be spread through unprotected sex, such as AIDS, syphilis, Hepatitis B, Hepatitis C, genital herpes, genital warts and other diseases. In fact, broadly speaking, high-risk sex refers to sex without any protection, such as male-to-male sex, male-to-female sex, female-to-female sex, multiple sexual partners, etc., which may become high-risk gender behavior.