Sexual transmission, blood transmission and mother-to-child transmission are the main ways of transmission, with sexual transmission being the most important, accounting for more than 90% of all transmission. The HIV virus is found in very small amounts in saliva, sweat, tears and other bodily fluids, which contain almost no virus. The virus is mainly found in the semen, blood, vaginal secretions, and breast milk of the patient, so the likelihood of having the virus on the hands is extremely low when the hands are intact. Also, the HIV virus cannot leave the body and survive in the air alone, so even a small amount of the virus on the hand cannot constitute transmission. However, if there is an open wound on the hand, a break in the mucous membrane of the skin, and the hand is contaminated with bodily fluids with HIV, it is possible to contract HIV. Prevention of AIDS requires avoiding unclean or casual sex and having too many sexual partners, as well as avoiding unnecessary blood transfusions, use of unclean extraction appliances or syringes, etc. Normal contact with people with AIDS in daily life and sharing public facilities does not lead to transmission.