HIV (Human Immunodeficiency Virus) is a virus that attacks the immune system, gradually weakening it over time. When left untreated, HIV can progress to AIDS (Acquired Immune Deficiency Syndrome), which is a more advanced stage of the disease. There is currently no cure for HIV/AIDS, but antiretroviral therapy (ART) can slow down the progression of the virus and help people with HIV live longer, healthier lives.