is caused by the human immunodeficiency
virus. You can get HIV from contact with infected blood, semen, or vaginal fluids.
Most people get the virus by having unprotected sex with someone who has HIV.
Another common way of getting it is by sharing drug needles with someone who is infected with HIV.
The virus can also be passed from a mother to her baby during pregnancy
, birth, or breastfeeding.
HIV doesn't survive well outside the body. So it can't be spread by casual contact like kissing or sharing drinking glasses with an infected person.