Human immunodeficiency virus (HIV) is a virus that attacks the immune system and weakens the body’s ability to fight infection and disease. A person with HIV can therefore develop serious infections that a healthy person could normally fight off. People infected with HIV who develop illnesses due to the damage caused by the virus are said to have acquired immune deficiency syndrome (AIDS). AIDS is the late stage of HIV infection, when the body has difficulty fighting life-threatening infections without treatment. There is no cure for HIV infection, but there are antiretroviral (ARV) treatments that work against the HIV infection by slowing down the spread of the virus in the body. ARV treatments help most people with the virus to live long and healthy lives.