AbstractHIV stands for human immunodeficiency virus. It weakens a person’s immune system by destroying important cells that fight disease and infection. The human immunodeficiency virus (HIV) targets the immune system and weakens people's defense against many infections and some types of cancer that people with healthy immune systems can more easily fight off. As the virus destroys and impairs the function of immune cells, infected individuals gradually become immunodeficient. Immune function is typically measured by CD4 cell count. The most advanced stage of HIV infection is acquired immunodeficiency syndrome (AIDS), which can take many years to develop if not treated, depending on the individual. AIDS is defined by the development of certain cancers, infections, or other severe long-term clinical manifestations. If HIV is not treated, it can lead to AIDS (Acquired Immunodeficiency Syndrome). There is currently no effective cure. Once people get HIV, they have it for life. Some groups of people in the United States are more likely to get HIV than others because of many factors, including their sex partners and risk behaviors. But with proper medical care, HIV can be controlled. People with HIV who get effective HIV treatment can live long, healthy lives and protect their partners.