The human immunodeficiency virus (HIV) is a retrovirus that causes HIV infection and over time transforms itself into the acquired immunodeficiency syndrome (AIDS). The virus attacks the important immune system cells such as helper T cells (specifically CD4+ T cells), macrophages, and dendritic cells of the human body. HIV gradually damages the immune system, which makes the host susceptible to a range of infections. It is transmitted through the direct transfer of bodily fluids such as blood, semen or breast milk. A major cause of transmission is sexual contact with an infected individual. Preliminary diagnosis of HIV infection is done with the help of enzyme-linked immunosorbent assay (ELISA) test, which tests the blood for the presence of HIV antibodies. Other tests include polymerase chain reaction (PCR) tests, western blot test, and single use diagnostic screening (SUDS) test. The treatment and management of HIV consists of the use of multiple antiretroviral drugs. Preventive measures such as condoms and vaccines can help reduce HIV transmission. Another significant type of prevention strategy is antiretroviral therapy. This book outlines the important aspects of HIV/AIDS infection in a comprehensible and lucid manner. It presents researches and studies performed by experts across the globe. This book will provide comprehensive knowledge to the readers.