You can get HIV by being involved in high-risk behaviors such as sexual intercourse with an infected person. The virus is carried in semen and vaginal fluids. These fluids come out during sex and are passed to the other person. You cannot destroy the virus by washing after sex. You can also get HIV by sharing needles for drugs, tattoos or ear piercing since it is carried in the blood.
Newborn babies can get the virus from their moms.
It's very rare to get it from blood transfusions since blood is now screened for the virus. However, a few years ago blood was not tested as carefully and some people who are ill today contracted the virus from a transfusion years ago. The only way you can get HIV from kissing is if both partners have bleeding sores or gums and an exchange of infected blood takes place. Remember that even brushing teeth can bring blood to the surface. There's also a very slight chance of getting the virus from a stranger who may be injured or bleeding.