AIDS stands for Acquired Immunodeficiency Syndrome. It's the most advanced stage of HIV infection. HIV (Human Immunodeficiency Virus) weakens the body's immune system by attacking white blood cells. HIV is spread through certain bodily fluids from an infected person, including: * Blood * Breast milk * Semen * Vaginal fluids It can be transmitted through unprotected sexual contact, sharing needles or syringes, and from mother to child during pregnancy, childbirth, or breastfeeding.