HIV diagnosis is the process of determining whether an individual has been infected with the human immunodeficiency virus (HIV), which is the virus that causes acquired immunodeficiency syndrome (AIDS). This typically involves a series of tests that detect the presence of antibodies to HIV in a person's blood, saliva, or urine. These tests can include rapid tests, enzyme immunoassays (EIAs), and nucleic acid tests (NATs). Early diagnosis of HIV is important for starting treatment and reducing the risk of transmission to others. There is ongoing research in improving existing testing methods and developing new technologies for more accurate and efficient diagnosis of HIV.