What Is HIV? What Is AIDS?
Human immunodeficiency virus (HIV) is a virus that attacks the immune system. (Both the virus and the infection it causes are called HIV.) People can get HIV from coming in contact with infected blood, semen, or vaginal fluids. Treatment for HIV can help people with infections live long, healthy lives. Treatment also often prevents the most severe stage of HIV infection, acquired immunodeficiency syndrome (AIDS). Learn more about HIV and AIDS.