What is the test looking for?

The HIV test is designed to detect antibodies to HIV in your blood or saliva. Antibodies are “fighter cells” produced by your body when you have an infection. If you are infected with HIV, your body makes very specific antibodies to fight the infection. The HIV antibodies are different from antibodies for the flu, hepatitis, or other infections. If you have HIV antibodies, then you have been infected with HIV. (The only exception to this applies to infants born to HIV-infected mothers; infants can receive HIV antibodies from their infected mothers that stay in their system for as long as 18 months.)
The HIV test does not tell you if you have AIDS or how long you have been infected or how sick you might be. It just tells you that you are infected with the virus