To expand upon the answers given to you by Teak and Lizzie;
HIV is the virus that can lead to AIDS. An HIV test will test for antibodies to the HIV virus in your bloodstream (though there are Saliva tests and I beleive some urine based tests). Someone who is HIV+ does not automatically have AIDS. A definition of AIDS is when the CD4 count is measured as being below 250.
During the course of the illness regular checks are made upon how the virus is progressing and how many copies of the virus there are against how the immune system is coping in fighting the virus.
A diagnosis of AIDS is made whenever a person is HIV-positive and:
he or she has a CD4+ cell count below 200 cells per microliter OR
his or her CD4+ cells account for fewer than 14 percent of all lymphocytes OR
that person has been diagnosed with one or more of the AIDS-defining illnesses listed below.
Candidiasis of bronchi, trachea, or lungs (see Fungal Infections)
Candidiasis, esophageal (see Fungal Infections)
Cervical cancer, invasive‡
Coccidioidomycosis, disseminated (see Fungal Infections)
Cryptococcosis, extrapulmonary (see Fungal Infections)
Cryptosporidiosis, chronic intestinal (>1 month duration) (see Enteric Diseases)
Cytomegalovirus disease (other than liver, spleen, or lymph nodes)
Cytomegalovirus retinitis (with loss of vision)
Encephalopathy, HIV-related† (see Dementia)
Herpes simplex: chronic ulcer(s) (>1 month duration) or bronchitis, pneumonitis, or esophagitis
Histoplasmosis, disseminated (see Fungal Infections)
Isosporiasis, chronic intestinal (>1 month duration) (see Enteric Diseases)
Lymphoma, primary, of brain (primary central nervous system lymphoma)
Mycobacterium avium complex or disease caused by M. Kansasii, disseminated
Disease caused by Mycobacterium tuberculosis, any site (pulmonary‡ or extrapulmonary)
Disease caused by Mycobacterium, other species or unidentified species, disseminated
Pneumocystis carinii pneumonia
Pneumonia, recurrent‡ (see Bacterial Infections)
Progressive multifocal leukoencephalopathy
Salmonella septicemia, recurrent (see Bacterial Infections)
Toxoplasmosis of brain (encephalitis)
Wasting syndrome caused by HIV infection†
The Content on this Site is presented in a summary fashion, and is intended to be used for educational and entertainment purposes only. It is not intended to be and should not be interpreted as medical advice or a diagnosis of any health or fitness problem, condition or disease; or a recommendation for a specific test, doctor, care provider, procedure, treatment plan, product, or course of action. MedHelp is not a medical or healthcare provider and your use of this Site does not create a doctor / patient relationship. We disclaim all responsibility for the professional qualifications and licensing of, and services provided by, any physician or other health providers posting on or otherwise referred to on this Site and/or any Third Party Site. Never disregard the medical advice of your physician or health professional, or delay in seeking such advice, because of something you read on this Site. We offer this Site AS IS and without any warranties. By using this Site you agree to the following Terms and Conditions. If you think you may have a medical emergency, call your physician or 911 immediately.