Human Immunodeficiency Virus, or HIV, is a virus that attacks the body's immune system, specifically targeting CD4 cells, which help fight infections. If left untreated, HIV can lead to Acquired Immunodeficiency Syndrome (AIDS), a condition where the immune system becomes severely weakened, making the body more vulnerable to infections and diseases. HIV is primarily transmitted through contact with infected bodily fluids, such as blood, semen, vaginal fluids, and breast milk. It can be spread through unprotected sexual contact, sharing needles, or from mother to child during childbirth or breastfeeding. Early diagnosis and treatment with antiretroviral therapy can help manage the virus and improve quality of life.