AIDS stands for Acquired Immune Deficiency Syndrome:

Acquired means you can get infected with it;

Immune Deficiency means a weakness in the body's system that fights diseases.

Syndrome means a group of health problems that make up a disease.

AIDS is caused by a virus called HIV, the Human Immunodeficiency Virus. If you get infected with HIV, your body will try to fight the infection. It will make "antibodies", special molecules that are supposed to fight HIV.

When you get a blood test for HIV, the test looks for these antibodies. If you have them in your blood, it means that you have HIV infection. People who have the HIV antibodies are called "HIV-Positive".

Being HIV-positive, or having HIV disease, is not the same as having AIDS. Many people are HIV-positive but don't get sick for many years. As HIV disease continues, it slowly wears down the immune system. Viruses, parasites, fungi and bacteria that usually don't cause any problems can make you very sick if your immune system is damaged. You don't actually "get" AIDS. You might get infected with HIV, and later you might develop AIDS.

You can get infected with HIV from anyone who's infected, even if they don't look sick, and even if they haven't tested HIV-positive yet. The blood, vaginal fluid, semen, and breast milk of people infected with HIV has enough of the virus in it to infect other people. Most people get the HIV virus by:

Having sex with an infected person.

Sharing a needle (shooting drugs) with someone who's infected.

Being born when the mother is infected, or drinking the breast milk of an infected woman.

Getting a transfusion of infected blood used to be a way people got AIDS, but now the blood supply is screened very carefully and the risk is extremely low.

Kim Bouldin-Jones addresses AIDS prevention in her video HIV/AIDS 101. Kim also explains how substance abuse often causes a person to make unhealthy decisions and choices that increase exposure to HIV and other sexually transmitted diseases in her most recent video Sex, Drugs & HIV.