HIV stands for human immunodeficiency virus. The virus can survive and grow only by infecting, and destroying, the immune system. This continual assault on the immune system makes it weaker and weaker until it is no longer able to fight off infections.

You can get HIV when an infected person's body fluids -- including blood, semen, fluids from the vagina, or breast milk -- get into your blood. That can happen through broken skin or the linings in your mouth, anus, penis, or vagina. Having unprotected sex with an infected person. Sharing a needle to take drugs.