AIDS means Acquired Immunodeficiency Syndrome.

ACQUIRED means you can get infected with it.
IMMUNO DEFICIENCY means a weakness in the body's system that fights diseases.
SYNDROME means a group of health problems that make up this 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," which are 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. These are called "opportunistic infections." (OI)

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 of the 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 their mother is infected, or sucking the breast milk of an  infected woman.
Getting a transfusion of infected blood.

HIV disease becomes AIDS when your immune system is seriously damaged. If you have less than 200 CD4+ cells or if your CD4+ percentage is less than 14%, you have AIDS. . If you get an opportunistic infection, you have AIDS. Opportunistic infections include Pneumocytosis carinii pneumonia (PCP), Kaposi's sarcoma (KS), Cytomegalovirus (CMV), candida which is a fungal infection that can cause thrush or infections in your throat or vagina. . If you get an opportunistic infection, you have AIDS.

There is no cure for AIDS at present. There are drugs that can slow down the HIV virus, and slow down the damage to your immune system. But there is no way to get all the HIV out of your body.

There are other drugs that you can take to prevent or to treat opportunistic infections (OIs). In most cases, these drugs work very well. The newer, stronger anti-HIV drugs have also helped reduce the rates of most OIs. A few OIs, however, are still very difficult to treat.